Troubleshooting 101 Asus/RMerlin Routers 2020

L&LD

Part of the Furniture
Top 10 Simple Asus/RMerlin firmware powered Router Troubleshooting steps to try first:
NOTE: Although this is for Asus/RMerlin-firmware powered routers, the steps below may be relevant to all routers, to get to a quick fix for common symptoms.​
  1. Check that the router’s System Time is accurate on the System Log tab.
    1. Check that the Time Zone and the ‘DST time zone changes’, start and end dates are correct too.
  2. Check that the available space for NVRAM and JFFS is sufficient (Tools, Internal Storage section).
    1. Also, check RAM too. Anything over 10MB 'free' should be sufficient. At least for mere routing duties.
  3. Check that HW acceleration is Enabled (Tools, Network section).
  4. Reboot the router via the GUI. Verify the GUI shows the router uptime as truly reset upon startup.
    1. Wait at least 10 minutes after the router has rebooted before doing any testing.
  5. Use google search for your issues with explicit search parameters. E.g. site:snbforums.com IPv6.
  6. Create a new, never-before-used SSID in the Guest network and test if it fixes any issues you may have.
    1. If step 5 solves your issues, create a new, never (ever) used/seen SSID by any of your devices (also see step 7 below).
    2. Instead, you can also reset each of your wireless client’s network sections or ‘forget’ each existing SSID from each client, reboot the device, and then re-associate to it. Personally, it is much easier to just use a brand new SSID.
  7. Use a 16-character username, an 8-character SSID, and 16-character passwords for the router and SSID’s that all have the following characteristics:
    1. Alphanumeric only.
    2. No spaces.
    3. No punctuation.
    4. No special characters.
    5. No smiley faces.
  8. Power off the router, physically remove the power plug from the router, and from the AC wall plug and wait 2 minutes or more before powering it up.
    1. If you have USB drive(s) connected; from the GUI, ‘Safely Remove’ them first (click on the USB drive within the GUI and then click the button to safely remove it for each one).
    2. Wait at least 10 minutes after the router has fully booted up before doing any further testing.
  9. Power off modem/ONT, remove the power plug from both the modem/ONT, and from the AC wall plug and wait at least 20 minutes, or ideally 1 hour.
    1. Also do step 8 in conjunction with step 9.
    2. Also, remove all Ethernet LAN and USB drives/cables from both the modem/ONT and from the router while they are off.
    3. When powering up, wait 5 minutes after the modem/ONT has powered up before turning on the router.
    4. Wait at least 10 minutes after the router has fully booted up before doing any further testing.
  10. Repeat step 9 but include the entire network now. Including switches, NAS, printers, scanners, gaming consoles, TVs, and all other client devices too.
    1. Remove all wired connections between networked devices including USB, Ethernet cables, and power from both the device and the wall AC power plug too.
If all of the above steps have been faithfully followed and the issues remain, and, the google search in step 4 does not yield any satisfying results, then the router is most likely in an unstable state and needs a full reset to factory defaults.

The M&M Config and the Nuclear Reset guides are suggested along with the guide in the following post to help get your router and your network to a good/known state where the firmware's expected defaults are used (properly) and available too.

https://www.snbforums.com/threads/ax88-packet-loss.62891/post-563326

TS101AsusRMerlin2020-07-27 by @L&LD
 

K-2SO

Very Senior Member
Good basic advice @L&LD, but some additional details:

1.2. Check CPU utilization. If a CPU core is always at 100%, something is wrong there. The CPU may be busy shortly after boot and during some operations, but always at 100% is not normal. Or multiple CPU cores dancing up and down for no apparent reason.

1.3. Check CPU temperature. Up to 80C in normal room conditions is OK. 100C is a problem indicator. Poor ventilation, perhaps. Get this router out of the closet or move it away from heat generating objects before you continue further with troubleshooting.

3.1. Check if LAN connections show expected connections/speeds. If Gb speed is expected, but 100Mbps is shown or not connected, something around cables/connections is wrong. Most devices have LAN port LEDs also showing connection speed. Quick visual inspection may reveal connection issues.

Anything over 10MB 'free' should be sufficient. At least for mere routing duties.
It is important to check what is taking the RAM, if the number is so low. This low number right after boot is a potential issue indicator. Buffers/Cache is OK. The system can reclaim this RAM when needed. If too many applications and bogus/duplicated processes occupy the RAM, then different approach is needed. What and why, SHH top, etc.

Check that HW acceleration is Enabled
Some folks prefer Game Device Prioritizing. It activates Traditional QoS and disables HW acceleration. Both types in newer routers. The only issue here is the maximum possible traffic processing, depending on the CPU. If the ISP speed is below the processing capabilities, this is not a problem whatsoever. Other firmware options also disable fully or partially HW acceleration, if not compatible.

Use a 16-character username, an 8-character SSID, and 16-character passwords
This is personal preference. Not a requirement.

Power off modem/ONT... and wait at least 20 minutes, or ideally 1 hour.
To get a different IP from the ISP's DHCP? This was recommended before when "DHCP not working properly" message appears. Asus software issue addressed in newer firmware versions. Included in Asuswrt-Merlin newer versions. No need to wait for nothing if no ISP DHCP issues are present. WAN/Special Requirements section, Continuous Mode is the best option to experiment with.
 
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L&LD

Part of the Furniture
1.2. Constant CPU utilization is one of the reasons to be looking for help. It won't help anyone to just 'see' it.

1.3. I have seen several models of routers that many of which normally operate above 80C. Even at 91C constantly, and even a couple at 96C (idle) and 98C (under load) the network stays 100% stable. Sure, lower temperatures help, but that isn't an issue for most routers. The SoC is rated for 120C or something close for most.

3.1 This is a two-second Google search. :)

Doesn't matter what is using the RAM. I've seen it go below 8MB and 'recover' on a couple of my own routers. Unless the network goes down or the router reboots, RAM usage is not usually an indicator of an issue.

Checking HW acceleration settings covers many 'issues', not just gamers.

I should have said that a 16-character username, is the maximum that the UI supports. Also, it should be different than the default 'admin'.

Some posts have been made that an SSID that is too short was causing issues. 8-characters isn't a preference, more like a minimum.

No, not just to get a different IP from the ISP. This works for many different issues that may otherwise be hard/impossible to track down otherwise.

@K-2SO, thanks for the feedback. :)
 

K-2SO

Very Senior Member
Checking HW acceleration settings covers many 'issues', not just gamers.
Enabled or Disabled are both normal states under specific conditions. I personally prefer HW acceleration disabled if the CPU has enough processing power.

The SoC is rated for 120C or something close for most.
Talking about @RMerlin supported router models, constant >100C requires attention. The CPU won’t burn, but may throttle or disable cores, affecting performance.

Doesn't matter what is using the RAM.
Popular belief is “Linux will take care of it”. The reality is manufacturers install just enough RAM to run their own firmware. Low available RAM right after boot requires attention, if not taken by Buffers/Cache.

This works for many different issues that may otherwise be hard/impossible to track down otherwise.
Example? 1h with no Internet may create even bigger issues. Ask your wife for further explanation. No Google search needed. :)
 

brec

Regular Contributor
Power off the router, physically remove the power plug from the router, and from the AC wall plug
I'm more comfortable with software than hardware. All I know about electricity is that electrons are yellow. I'm just curious about "and from the AC wall plug." What difference could that make?
 

K-2SO

Very Senior Member
What difference could that make?
@L&LD likes to reset things. Reset of the power adapters, perhaps? Unplugging LAN cables from powered down devices is another interesting step. Reset of the LAN cables, perhaps? I don’t know. I recently updated a server rack with >100 cables inside and >250 clients. Steps 9-10 would have extended the work with 2 more days.
 

brec

Regular Contributor
Reset of the power adapters, perhaps?
Dunno what those are... For unplugging AC cable from the wall after unplugging from modem to do something, they must be in the wall, or the breaker box?
 

L&LD

Part of the Furniture
@brec, when you physically disconnect everything from everything else, you are letting built-up charges (static electricity) dissipate that may affect the expected actions of those yellow electrons. One doesn't have to believe it works, but it may.

This thread is about quick fixes for home networks, that I have seen work repeatedly, that nothing else seems to fix. Not about commercial installations with greater than one hundred Ethernet runs and with over 250 clients.

And I'm not just about resetting things. I'm about getting networks, to work. Contribute where you can, but if this below your paygrade, move on, and thank you.

Here's another one for you guys. When an Ethernet LAN cable isn't working and you have the capability, (physically) reverse it. No guarantee it will work, but I've seen stranger things on networks that got things working (at least temporarily, until the replacement showed up). Btw, this doesn't just work on Ethernet cables either (HDMI, USB, Audio, etc.). :)

For me in my daily job, this (shortened) list is what makes me look like a rock star if these 'easy' fixes work. And is what I have come to call 'common sense' for the networking/electronics sector I work in.

But you know what isn't common for most people.

That is who this list is for.
 

bbunge

Very Senior Member
Overkill as usual. I have used 3 to 5 character SSID's for years with no issues. As for power off, a capacitor can hold a charge forever under the right conditions. And do not mess with the router when the wife is shoppjng!
 

K-2SO

Very Senior Member
Contribute where you can
About unplugging both power connector and power adapter - for the reason mentioned by @bbunge above, the better way is to leave the power cord in place with the device power button ON and unplug the adapter from the wall only. The device itself will discharge all the capacitors faster. I would suggest physical power adapter examination. Overheating, cable damages, plug damages, etc.

No special characters.
In addition to @bbunge comment above about SSIDs, I have multiple networks around with "_", "-", "." and "space" characters in SSID names. Are you saying Asus specifically has issues with SSIDs with non alphanumerical names? All those networks around seems to be working fine. Asus' own Guest Network suggested name was like Asus_XX_5G_Guest. What's the problem with that?

you are letting built-up charges (static electricity) dissipate
You can't do that by unplugging the cable. Where those charges go if the cable is unplugged? Homes don't have very long cable runs and CDE are unlikely. In commercial applications what you advice is actually more likely to damage equipment. Google "cable discharge event" for more information. Your own clothes and body may transfer static charges to unplugged equipment. Have you seen those grounding wrist straps?

When an Ethernet LAN cable isn't working
When a LAN cable isn't working it will show in Tools/Network or port physical LEDs. You don't have to tear down the entire network to fix one LAN cable connection. Troubleshooting and doing all over again are different things. You prefer do all over again approach. Both in hardware and software. Sometimes LAN ports have issues. Unplugging the cable and plugging it back in the same port won't fix anything. Plugging it in a different LAN port may help.
 
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CriticJay

Senior Member
Some people are skeptical about why we would "turn everything off and turn everything back on" as part of network troubleshooting ... but here's a real-world example from my weekend:

I have a Samsung Q70R smart soundbar. The thing is, it's ALWAYS on (even when you turn it off) and once you associate it with a WiFi SSID, it'll *always* be connected to that SSID. Also, there's no way to "reboot" it, even using the Samsung SmartThings app. So, if I want to reboot the embedded Linux OS (most likely) running this soundbar, the only thing I can do is physically unplug it, wait a short while, and plug it back in.

There can be many reasons I would need to do this, especially if I'm experimenting with settings on the router i.e. Changing its DHCP reserved IP address, playing with DoT on/off, etc. etc. etc. Or even making changes to my Samsung cloud account, I would need to unplug/re-plug the soundbar to get it to refresh my Samsung account...

So let's not underestimate the value of unplugging things/turning things off and turning them back on, especially in this age of IoT devices which we have very little direct control over, unlike our Windows 10 Laptops.
 

L&LD

Part of the Furniture
@bbunge, sure, overkill for you. Not for the people who had issues that this 'fix' provided them though.

@K-2SO, the very fact of disconnecting and reconnecting cables/devices dissipates static charges. In many cases enough to merit doing so in the first place. You can keep producing examples of why some of my points may not work for everyone, but it doesn't negate the fact that in some circumstances, they do.

If you don't have anything positive to add here, please ignore this thread.

And to point out one more distinction you seem to miss (a lot), unplugging a cable, reversing ends, and plugging it back into the same ports/equipment has worked enough times that it bears repeating and sharing here, contrary to your negative outlook on the outcome it 'should' provide.
 

K-2SO

Very Senior Member
The thing is, it's ALWAYS on
You have no other option to turn completely OFF devices that stay always ON when plugged in power outlet. That applies for TVs, Game consoles, Speakers, etc. No need to unplug the cord in 2 places though.

the very fact of disconnecting and reconnecting cables/devices dissipates static charges
Incorrect. Step 5 on your list, Google search.

If you don't have anything positive to add here, please ignore this thread.
No problem. Not a fan of wasting time in chaotic troubleshooting anyway. :eek:
 

L&LD

Part of the Furniture
Again, you keep missing the important distinction(s) I make. We're not doing scientific tests in deep space somewhere past Saturn while using the latest lab equipment only countries can afford to show a static charge (or not).

Fully quoting myself from post twelve above.

the very fact of disconnecting and reconnecting cables/devices dissipates static charges. In many cases enough to merit doing so in the first place.

All we need is enough of a change to make our networks, work. Not discharge the equipment absolutely.
 

RMerlin

Asuswrt-Merlin dev
@K-2SO, the very fact of disconnecting and reconnecting cables/devices dissipates static charges.
It doesn't. He was correct, the proper way to discharge all power is to have the device turned on while the AC is unplugged. It will cause any residual power charge to get dissipated from the capacitors.

That's why I always had a precise procedure when I told people to do an "electrical reset", which involved unplugging the AC and turning the device on then off again.
 
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L&LD

Part of the Furniture
RMerlin, I'm sorry, but of course, making/breaking connections dissipates static charges. As does leaving devices powered off for a certain length of time. I am not talking about the residual power to capacitors and such.
 

K-2SO

Very Senior Member
I'm sorry, but of course, making/breaking connections dissipates static charges.
It doesn't @L&LD. You need grounding. You just waste your time standing on the carpet/hardwood floor and touching/moving cables with your hands. At least one of the devices connected to those cables must be grounded. None of those with power adapters and 2-wire cables are. Talking about residual capacitors charge, unplugging the device first and then the power adapter increases the chances to have residual charge in power adapter. Most have discharging resistors on the output, but will discharge faster if the device is plugged in.

As does leaving devices powered off for a certain length of time.
Also incorrect. Static electricity charge doesn't come from device operation. You can zap a computer part right after taking it out of the protective bag. This part may be sitting there "unplugged" for years. With no grounding you only transfer static charges from one object to another.
 
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L&LD

Part of the Furniture
We're not talking about static electricity between insulators here. We're talking about potential differences between two or more pieces of equipment. Once connected, the charge between them has effectively dissipated. I don't know how to make this idea simpler for you.
 

K-2SO

Very Senior Member
Once connected, the charge between them has effectively dissipated. I don't know how to make this idea simpler for you.
That's the problem. The idea is wrong. With no grounding charges just transfer from one object to another until they equalize. If your body carries a charge, you just transfer it to the equipment, unless you touch a metal grounded object before that.
 

routerbattles

Occasional Visitor
Some really solid advice here with some great links to posts i only found after a fair bit of digging previously. Should help in Google searches too poss? Thanks for this.
Potential sticky?
 

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