RT-AC3200 WAN stuck on 100 Full Duplex

[Jeff Rudolph]

Hello, been pulling my hair out trying to figure out why my internet speeds out of my RT-AC3200 wired ports seem to be maxed at 100Mbps, and I think its related to the WAN being stuck on 100 Full Duplex.

I have Merlin FW 384.13_2.

When I go to Tools > Settings > Network is says ->
Port VLAN Link State
WAN 2 100 Full Duplex

In robocfg it says ->
jdrudolp@RT-AC3200-CBE0:/tmp/home/root# robocfg show
Switch: enabled
Port 0: 100FD enabled stp: none vlan: 2 jumbo: off mac: 00:cc:fc:61:a4:22
Port 1: DOWN enabled stp: none vlan: 1 jumbo: off mac: 00:00:00:00:00:00
Port 2: DOWN enabled stp: none vlan: 1 jumbo: off mac: 00:00:00:00:00:00
Port 3: DOWN enabled stp: none vlan: 1 jumbo: off mac: 00:00:00:00:00:00
Port 4: 1000FD enabled stp: none vlan: 1 jumbo: off mac: 00:22:4d:51:9b:e6
Port 5: 1000FD enabled stp: none vlan: 2 jumbo: off mac: ac:9e:17:a9:cb:e0
Port 7: DOWN enabled stp: none vlan: 1 jumbo: off mac: 00:00:00:00:00:00
Port 8: DOWN enabled stp: none vlan: 1 jumbo: off mac: 00:00:00:00:00:00
VLANs: BCM5301x enabled mac_check mac_hash
1: vlan1: 1 2 3 4 5t
2: vlan2: 0 5
1045: vlan1045: 0t 1t 5
1046: vlan1046: 5t 8t
1047: vlan1047: 0 2 3t 5
1099: vlan1099: 1 2 7t 8t
1100: vlan1100: 3 4 7t
1101: vlan1101: 0 3 7
1102: vlan1102: 1t 5t
1103: vlan1103: 0 7 8t

I tried to force Port 0 to 1000FD with "robocfg port 0 media 1000FD" but when I did that, running robocfg show again gave me "Port 0: DOWN" and i had to reboot the router which returning it to "Port 0: 100FD".

I have seen some similar posts to this, but nothing has worked. I tried swapping out the cables. Any ideas? Thanks! Jeff

 

[ColinTaylor]

Has this ever worked at gigabit before? In other words is this a recent development?

Make sure the interface on the cable modem is also supports gigabit.

 

[Jeff Rudolph]

That's a good question, I never looked before My internet speed was only 50mbps, but through a promo I ended up with 300Mbps for the same price. The comcast guy was here today and we tracked the speed from link to link and it was ~375 all the way to my computer directly connected to the cable modem, where it was around 200. But once I added the router between the cable modem and my computer it dropped to 97Mbps. So im pretty sure the cable modem supports gigabit, since it was getting ~200 straight from it at my computer.

 

[System Error Message]

try a different cable

 

[degrub]

Was the cable used to connect from the ISP modem to the PC during the cable speed test the same one used to connect to the wan port of the router ?
If so, try factory reset of the router and see what you get. Then manually reconfigure the router if the speed was ok.

 

[Jeff Rudolph]

I did try two cables, and the cable between the ISP modem and the PC during the cable speed test was the same one used to connect to the wan port of the router. I will try another set of factory resets, I'll try to factory reset the cable modem too just in case there is some stale entry in it that is preventing it from auto detecting 1000Mbps with the router.

 

[Jeff Rudolph]

So grabbed a third cable and did some more testing, I have ruled out the cables, the cable modem, and my computer at this point. I can reliable get 350Mbps from dslreports speed test going straight from my cable modem to my computer. Once I put the RT-AC3200 router back into the loop, my computer slows to 95Mbps. I have been trying to factory reset my AC3200 but it always comes back up with the latest Merlin FW I loaded on it to get the Tools tab to come up. Seems like at this point I might need a new router, perhaps I can find a friend's router or extra to borrow and try that.

 

[L&LD]

A full factory reset to factory defaults will not give you back the firmware you originally bought the router with. Rather, it will fully clear all the registers and variables to the current firmware's defaults.

It should give you the Setup Wizard to set up the router though if it was really reset properly.

To make sure your router is in a good/known state, flash the same firmware it currently has and do an additional reset to factory defaults including checking the box to 'Initialize all settings...' via the GUI.

 

[Jeff Rudolph]

Ah ha! Well that's good to know, I always thought factory reset would pull a factory FW from a PROM as well as reset any settings, etc., etc. You learn something new every day!!

So in reading another thread on this topic (https://www.snbforums.com/threads/a...s-wan-dhcp-does-not-function-correctly.56682/) I didn't even realize I could use a different port for my WAN. So I made LAN Port 2 a double WAN, as the primary, with my WAN as the secondary. I moved the wire and viola! 350Mpbs!!! So looks like my WAN port itself is defective/damaged/needs cleaning. Interesting I tried LAN Port 4 first because it was empty and right next door to the WAN port and that one didn't even light up. I've been only using 1, 2, & 3 plus the WAN at 25Mpbs for 5 years so I never noticed a difference. At any rate, for now, I'm good! If I ever want more ports I guess I'll either need a new router or to buy a switch or two.

Thanks all for your replies and keeping me going to figure this out!

 

[L&LD]

@Jeff Rudolph, learning is a two-way street. I, as I'm sure many others here, appreciate the time you took to reply and give us the solution that worked for you.

I'll have to add one more step in my list of things to test before I 'throw out the router with the baby' next time.