ASUS RT-AC1750-B1, 5G connection unstable

[asuswoes]

Hello,
Reaching out here as a last attempt to hopefully resolve this issue before switching away from ASUS routers.

I recently switched from cable to fiber and replaced the old ISP's modem/router combo (Hitron CGN2) with my own router (RT-AC1200G).

My mobile client (Galaxy S3) kept randomly reconnecting on the 5G frequently; something I have never seen happen on 5G in the past with several other routers.

After some troubleshooting and no luck, I had it replaced and had the same issue with the new one.
I figured it was a hardware issue and replaced it with the RT-AC1750-B1 (as noted in gateway config) instead and have experienced the exact same issues with this one too.
I have tried most of the troubleshooting tips I've found on this forums and others, to no avail.

Symptoms:
Every 2 hours or so, my mobile client will drop 5G and quickly reconnect twice in succession. (sometimes once, but usually twice)

I set the system logger to log all events and view > Debug and the strange thing is that it doesn't show any errors, all it shows is that the client disconnected and reconnected twice when these drops occur.
When the client drops, the 5G light on the router is still on, however the client cant see the 5G SSID, although it does still find the 2.4G SSID.

Mobile client works fine on other 5G networks (work, friends house etc.)


Troubleshooting:
-Factory reset and updated firmware to Merlin
-Used wifi analyzer to find an adequate channel (tried 40, 44 and 48, Canada)
-Tested 20, 40 and 80 mhz individually
-Only 20 feet away and signal is fairly strong, never below 3 bars. (The apartment is only 500sqft)
-Disabled QoS
-Disabled NAT Acceleration
-Made sure the SSID for 2.4G and 5G are different. Even disabled 2.4G entirely
-Temperatures are stable at 48C for 5G
-Memory and CPU usage are very low
-Router is sitting on desk, unobstructed (same place as old router) and no wireless/bluetooth devices nearby
-There's only a handful of neighboring 5G connections and none are on my channel
-I have no other wireless devices
-I mostly use wifi between 10pm-8am, so a much lower chance of interference
-I'm sure there's others I'm forgetting since I've been troubleshooting this for weeks

I'm completely stumped on what to do next; I would love to keep the router but at this rate I feel like it's just the ASUS routers that all seem to be defective.
Any help would really be appreciated.

 

[scjr]

Have you tried manually assigning that device an IP address? That’s worth a try.

 

[asuswoes]

Have you tried manually assigning that device an IP address? That’s worth a try.

Thanks for the suggestion.

I can give it a try; any specific reason why that would make a difference though?
I've noticed from the logs that the client still has the same ip as it did prior to the disconnect/reconnect cycle.

 

[scjr]

Thanks for the suggestion.

I can give it a try; any specific reason why that would make a difference though?
I've noticed from the logs that the client still has the same ip as it did prior to the disconnect/reconnect cycle.

Some clients don’t play well with dhcp. I know my Apple devices do better with assigned addresses. Had issue once where one had trouble negotiating with router. Assignment fixed it. Worth a shot.

 

[asuswoes]

Some clients don’t play well with dhcp. I know my Apple devices do better with assigned addresses. Had issue once where one had trouble negotiating with router. Assignment fixed it. Worth a shot.

So I disabled DHCP, set up a manual IP and configured the client to pick up the static IP.
No luck, unfortunately.

 

[scjr]

So I disabled DHCP, set up a manual IP and configured the client to pick up the static IP.
No luck, unfortunately.

Keep dhcp enabled and just manually assign that one device in the router. Don’t do anything with the device. What’s your lease time set to? Is this the only device that has this issue?

 

[asuswoes]

Keep dhcp enabled and just manually assign that one device in the router. Don’t do anything with the device. What’s your lease time set to? Is this the only device that has this issue?

To clarify, I initially set up the manual IP with DHCP enabled. The random intermittent drops still occurred.
I then disabled the DHCP and manually assigned the IP to the SSID config on the client, which still didn't prevent the drops.

The lease time is the default value of 86400, I believe.

Looking further into this, I just realized that I may not have flushed out the nvram when I initially did the factory reset and updated to Merlin, as per this guide:
https://www.snbforums.com/threads/faq-nvram-and-factory-default-reset.22822/

The factory installed firmware was 4-5 versions outdated, so it's very likely that if this is a bug which has been resolved, my nvram might still be holding on to old settings.
I'm going to reflash Merlin and flush the vram tonight. Fingers crossed.

 

[scjr]

Looking further into this, I just realized that I may not have flushed out the nvram when I initially did the factory reset and updated to Merlin, as per this guide:
https://www.snbforums.com/threads/faq-nvram-and-factory-default-reset.22822/

The factory installed firmware was 4-5 versions outdated, so it's very likely that if this is a bug which has been resolved, my nvram might still be holding on to old settings.
I'm going to reflash Merlin and flush the vram tonight. Fingers crossed.

That might be it. Good luck and keep us updated!

 

[asuswoes]

So I ended up reflashing and wiping the vram.
Unfortunately, it still didn't make a difference.
5g still has intermittent reconnect issues.

This is basically what I see in the log during the time of the reconnects:

Dec  3 06:16:40 dnsmasq-dhcp[1129]: DHCPREQUEST(br0) 192.168.50.3 5c:0a:5b:6d:a9:43
Dec  3 06:16:40 dnsmasq-dhcp[1129]: DHCPACK(br0) 192.168.50.3 5c:0a:5b:6d:a9:43 android-609faaad4c2c9729
Dec  3 06:38:46 dnsmasq-dhcp[1129]: DHCPREQUEST(br0) 192.168.50.3 5c:0a:5b:6d:a9:43
Dec  3 06:38:46 dnsmasq-dhcp[1129]: DHCPACK(br0) 192.168.50.3 5c:0a:5b:6d:a9:43 android-609faaad4c2c9729
Dec  3 06:42:36 dnsmasq-dhcp[1129]: DHCPREQUEST(br0) 192.168.50.3 5c:0a:5b:6d:a9:43
Dec  3 06:42:36 dnsmasq-dhcp[1129]: DHCPACK(br0) 192.168.50.3 5c:0a:5b:6d:a9:43 android-609faaad4c2c9729

 

[asuswoes]

It's been a while, but I ended up replacing the router with a DLink DIR-878.
It worked fine for a couple of days and then back to the same issue; 5G dropping and intermittently reconnecting.

I was able to run a wifi analyzer, night right away when I noticed a disconnect and although the 5G signal was still active and stable, the quality of several channels had dropped significantly, including the channel my 5G was on (usually they're 90-100%, but they were down to 20% for several seconds).

Seems like my phone's wifi receiver is acting up since I moved, either that or the building, or floor I'm on is picking up some anomalous interference.
Unfortunately I'll have to live with the issue as I have no other wireless devices to test but the chances of 4 different routers with the exact same hardware issue seems unlikely. I have to conclude the ASUS AC1750 is (probably) fine.

Either way, looks like nothing more to add to this thread; I'll stick with the ASUS and return the D-Link as I prefer the advanced configuration options and usability.