Hello.
A few months ago I flashed my ASUS RT-AC85P router with OpenWRT 21.02.3 firmware. Everything has been working great, but I have recently noticed that my internet speed wouldn't go past 95 mb/s, which is well below what my ISP provides (200 mb/s). To test the speed connection I used the dslreports speed test, as well as a few others.
I contacted my ISP - they assured me everything was right on their end and the issue has to be on my end, so I began troubleshooting.
Eventually, I think I narrowed down the problem to the 'wan' interface being limited to 100mb/s by the router for some reason.
Here's what I've tried:
1. Connecting the ethernet cable directly to my PC, omitting the router
This fixes the problem, my internet speed went back to the full 200 mb/s - tested with the dslreports test again.
I have also repeated this with every ethernet cable that I'm using - they're all working fine and providing the full 200mb/s speed. All the cables I use are ethernet cat5e cables, which should be capable of handling 1Gb/s speed.
I believe this eliminates the possibility of a faulty ethernet cable.
2. Googling for people experiencing similar issues
This has brought me to various threads on the OpenWRT forums.
The first one I found suggested running the following command for further troubleshooting:
dev=$(ifstatus wan | grep "device | awk '{print $2}' | sed 's/"//g;s/,//g'); echo "Interface: $dev, Speed: $(cat /sys/class/net/$dev/speed)"
The output of the command ran on my device is:
Interface: wan, Speed: 100
At this point I knew this output wasn't what it should be and suspected that the issue is my router somehow establishing wrong connection speed.
3. ethtool
After further googling, I obtained more information with the ethtool utility.
I ran the following commands and obtained the following output:
ethtool eth0
Settings for eth0:
Supported ports: [ MII ]
Supported link modes: 1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: No
Supported FEC modes: Not reported
Advertised link modes: 1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: No
Advertised FEC modes: Not reported
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Current message level: 0x000000ff (255)
drv probe link timer ifdown ifup rx_err tx_err
Link detected: yes
ethtool wan
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Link partner advertised pause frame use: No
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 100Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: external
Auto-negotiation: on
Supports Wake-on: d
Wake-on: d
Link detected: yes
Just like before, I believe this output points out where the issue lies. Unfortunately, I lack the understanding of this part of networking and I don't know why the wan
interface is limited to 100mb/s and doesn't advertise 1000mb/s as the option like other interfaces.
I then tried forcing the speed of the wan
interface to 1000 with the ethtool utility with the following command:
ethtool -s wan speed 1000 duplex full autoneg on
But that broke internet connectivity entirely and I had to fix it with ethtool -s wan autoneg on
to bring it back on. The interface reverted to 100mb/s again.
At this point I have no idea how to fix this issue. Before I switched to OpenWRT as my firmware I had the full internet speed.
I'd appreciate if someone could offer ideas on how to fix or further troubleshoot the issue.