Solved Down speed capped ~100mbps (GT-AC2900)

[hoodles]

I am paying for 500mbps down from my ISP, which I can get if wired directly to the modem. However, I'm getting no more than 95mbps when the GT-AC2900 is anywhere in the stream. Speed tests are consistent across wired device, wireless device, as well as the test directly in the router's web interface.

I have performed factory reset, updated firmware to latest (3.0.0.4.386_51529), and am using the ethernet cable where I confirmed 400+mbps directly from the modem. I also tried enabling Dual WAN and setting primary WAN port to LAN1 in case of faulty port.

Not getting much help from official ASUS support, so hoping for some bright ideas here.

Edit: Solved, but I don't have much advice to any future Googlers. Things just started...working.

 

[Darkje]

What's the link speed... I think 100

 

[Tech9]

Not getting much help

What is the Status page saying for Ethernet Ports?

 

[hoodles]

@Tech9 Ports are at 1gbps

I did some speed tests in the router interface as well, so I would assume the LAN ports wouldn't matter too much.

 

[hoodles]

Results for posterity:

Direct connection to modem

Router interface speed test

Wired to router

 

[drinkingbird]

Results for posterity:

Direct connection to modem
View attachment 52667

Router interface speed test
View attachment 52668

Wired to router
View attachment 52669

You sure you don't have QOS enabled in the Asus, set to say 100M from a previous internet speed?

 

[bennor]

I have performed factory reset, updated firmware to latest (3.0.0.4.386_51529)

Have you tried a hard factory reset?
[Wireless Router] ASUS router Hard Factory Reset - Method 2

When you configured the router after updating the firmware did you reload a previously saved/exported router configuration file?
Have you enabled any additional options like QoS or AiProtection?

 

[hoodles]

You sure you don't have QOS enabled in the Asus, set to say 100M from a previous internet speed?

QoS is disabled

Have you tried a hard factory reset?
[Wireless Router] ASUS router Hard Factory Reset - Method 2

When you configured the router after updating the firmware did you reload a previously saved/exported router configuration file?
Have you enabled any additional options like QoS or AiProtection?

I did perform the method you linked (as well "Factory default" restore using Administration page in router), and while the settings were returned to default and wireless network needed to be setup again, I was surprised that the latest firmware was maintained. I figured the firmware would be returned to the version it left the factory with.

Anyway, after reset I did not reload a previous config or change any settings. Just the minimum to get into the main web interface: set wireless SSID and router admin user/password.

 

[Tech9]

Ports are at 1gbps

The speed is capped to Fast Ethernet. I would try with a different cable.

 

[drinkingbird]

QoS is disabled

View attachment 52670

Can you get over 100M transfer speed between two LAN ports, or wireless to LAN etc? You can use iperf or just a file transfer (convert bytes to bits if file transfer).

Something really seems to be a physical 100M limit (93M is about right with overhead) but I suppose it could just be coincidence.

There are instances where one side sees gig and the other sees 100M if the cable has one or two bad connections out of the 8. Sometimes it will make good contact in one RJ45 port but not another.

 

[hoodles]

The speed is capped to Fast Ethernet. I would try with a different cable.

I have tried a couple different cables. Also, I used the same cable that got 500+mbps from modem-to-device for the modem-to-router WAN connection. Wouldn't this discount the cable being the problem?

Can you get over 100M transfer speed between two LAN ports, or wireless to LAN etc? You can use iperf or just a file transfer (convert bytes to bits if file transfer).

Something really seems to be a physical 100M limit (93M is about right with overhead) but I suppose it could just be coincidence.

There are instances where one side sees gig and the other sees 100M if the cable has one or two bad connections out of the 8. Sometimes it will make good contact in one RJ45 port but not another.

Unfortunately my desktop is being rebuilt, so I have to use wired laptop and smartphone. However with iperf server on laptop and phone as sending client, I am seeing 250-300Mbps, which I assume disproves any hard limit through the router.

 

[drinkingbird]

I have tried a couple different cables. Also, I used the same cable that got 500+mbps from modem-to-device for the modem-to-router WAN connection. Wouldn't this discount the cable being the problem?


Unfortunately my desktop is being rebuilt, so I have to use wired laptop and smartphone. However with iperf server on laptop and phone as sending client, I am seeing 250-300Mbps, which I assume disproves any hard limit through the router.

View attachment 52672

Technically you aren't routing LAN to LAN just wanted to start to narrow it down. So it is either the connection between the ISP modem and router WAN or something in the router itself (when routing LAN to WAN). You know your LAN and WIFI are both good at this point. You could give the router WAN and your laptop a static IP, plug laptop into the WAN port and try doing Iperf to test the router WAN port and routing ability. Without configuring port forwarding or disabling NAT and adding static routes, will only be able to test in one direction (initiated from phone to laptop, download direction) but that is fine as that simulates the same as speed test.

Does the ISP modem have lights on it or anything in the GUI that will show you the link speed on the LAN port? Is it a plain modem or a router (even if in bridge mode)?

Keep an eye on the router CPU during the speed test too, it definitely should not be limiting you to 93M but just another point to rule out.

 

[hoodles]

Technically you aren't routing LAN to LAN just wanted to start to narrow it down. So it is either the connection between the ISP modem and router WAN or something in the router itself (when routing LAN to WAN). You know your LAN and WIFI are both good at this point. You could give the router WAN and your laptop a static IP, plug laptop into the WAN port and try doing Iperf to test the router WAN port and routing ability. Without configuring port forwarding or disabling NAT and adding static routes, will only be able to test in one direction (initiated from phone to laptop, download direction) but that is fine as that simulates the same as speed test.

Does the ISP modem have lights on it or anything in the GUI that will show you the link speed on the LAN port? Is it a plain modem or a router (even if in bridge mode)?

Keep an eye on the router CPU during the speed test too, it definitely should not be limiting you to 93M but just another point to rule out.

Standalone modem is provided by Spectrum so no available GUI page and status lights are the basic Power/Online. Would link speed possibly change from 1G to 100M depending on direct connection to device vs router WAN?

Router CPU has barely any utilization during speed test. Like <5% on both cores.

Would the test that assigned Dual WAN primary to LAN1 cover the case you're talking about, or is it less the physical WAN port and more the actual routing that we're trying to test?


Thank you for the help so far!

 

[bennor]

Standalone modem is provided by Spectrum

It may help others with diagnosing if you post the specific modem model.

 

[Tech9]

GT-AC2900

Where this router came from?

I have tried a couple different cables.

Inspect the WAN port carefully, look at the pins condition, clean it if needed.

 

[hoodles]

It may help others with diagnosing if you post the specific modem model.

Sorry about that. Looks to be a DOCSIS 3.1, model Hitron E31N2V1.

I had my own DOCSIS 3.0 before switching to Spectrum, but I seem to recall that they required I use theirs (or at least a DOCSIS 3.1 capable modem).

 

[drinkingbird]

Standalone modem is provided by Spectrum so no available GUI page and status lights are the basic Power/Online. Would link speed possibly change from 1G to 100M depending on direct connection to device vs router WAN?

Router CPU has barely any utilization during speed test. Like <5% on both cores.

Would the test that assigned Dual WAN primary to LAN1 cover the case you're talking about, or is it less the physical WAN port and more the actual routing that we're trying to test?


Thank you for the help so far!

Modem should be reachable via http://192.168.100.1 though info may be limited. The test is to confirm a couple things, if it exceeds 100M you've ruled out the Asus completely at that point.

 

[hoodles]

Where this router came from?



Inspect the WAN port carefully, look at the pins condition, clean it if needed.

Bought it off Amazon. And WAN port looks fine. I mentioned earlier that I tried using LAN1 as primary WAN via Dual WAN mode with no changes, so unless both ports have issues the problem probably isn't there.

 

[hoodles]

Modem should be reachable via http://192.168.100.1 though info may be limited. The test is to confirm a couple things, if it exceeds 100M you've ruled out the Asus completely at that point.

I can't seem to access the modem at http://192.168.100.1 via browser or ping. Spectrum may have blocked it on these devices; it wouldn't surprise me.

Edit: A user on reddit seems to confirm my suspicions:

Spectrum locks the modems so you can't access the config page at 192.168.100.1

I'll try the iperf test when setting static IP on laptop/router WAN. I think I see what you're getting at, but haven't tried something like that before.

 

[drinkingbird]

I can't seem to access the modem at http://192.168.100.1 via browser or ping. Spectrum may have blocked it on these devices; it wouldn't surprise me.

Edit: A user on reddit seems to confirm my suspicions:


I'll try the iperf test when setting static IP on laptop/router WAN. I think I see what you're getting at, but haven't tried something like that before.

Router WAN static IP 10.0.0.1 255.255.255.0 (don't worry about DNS or gateway)
Laptop wired LAN static IP 10.0.0.2 255.255.255.0 (don't worry about DNS or gateway)
Laptop into airplane mode or disable wifi
iperf -s on laptop
iperf client to 10.0.0.2 on your phone.

While you're at it see what physical link speed the laptop and router are reporting. Both should be 1000. Would be nice to confirm duplex but you have to run a powershell command in windows and go into the CLI on the router to see that. Unlikely that it would be negotiating to 1000/Half (and that wouldn't explain the 93 megs either unless it was one heck of a coincidence).

If it exceeds 100, have ruled out the router as the issue
if it is limited to under 100 still, we know to focus on the router.

If it exceeds 100 my best guess is some strange negotiation issue between asus and the modem.