ASUS RT-AC3100 speed limit

[Marc Hertz]

Why does the WAN port on the ASUS RT-AC3100 seem to be set and limited to 100 Mbps instead of the specified 1 Gbps?

After weeks of testing, 11 service tickets, multiple phone calls and exchanging one router for another new one at the direction of ASUS user support I am still unable to get anything more than half the data transfer speed through the router that I am receiving with a direct connection to an Arris Surfboard8200 modem (ASUS RT-AC3100 LAN: 95 Mbps vs ARRIS SB82000: 180 Mbps). The technical specifications of the ASUS RT-AC3100 router state the LAN ports and 5Ghz wireless are rated at 1Gbps. But connections through the router consistently and repeatedly test at less than 100 Mbps.

When I view the Status of the network the router displays Port: WAN > Status: 100Mbps. Does this mean it is limited to 100Mbps and if so, why?

For both routers tested :
Latest firmware
multiple Cat5e cables
changed IP of router
added MAC address of router
QoS not enabled

 

[Grisu]

the WAN port set on the ASUS RT-AC3100 appears to be limited to 100 Mbps instead of the specified 1 Gbps.
When I view the Status of the network the router displays Port: WAN > Status: 100Mbps. Does this mean it is limited to 100Mbps and if so, why?

Yes it does mean your port is running 100M only!
We cant know why, either cable, bad port slot or connector, wrong cable with only 4 wires instead of full 8 wiring, wrong setting to limit to 100M.
Look inside WAN port, is one pin not parallel up like the others?

 

[Smokindog]

I'd suspect the cable you're using and/or the port on the other side of the cable. I've got 3 AC3100's and they'll connect at Gbs as advertised. I've not measured them specifically, that's the "connection speed".

 

[L&LD]

I think a full reset to factory defaults will fix this.

Please see my signature below for the link to the M&M Config to get your router to a good/known state.

 

[RMerlin]

I think a full reset to factory defaults will fix this.

Switch port negotiation has nothing to do with the firmware configuration. It's all handled at the hardware level.

I remember some people in the past had issues with the SB6200. They generally resolved the issue by using a cheap network switch between the modem and the router.

 

[Marc Hertz]

Yes it does mean your port is running 100M only!
We cant know why, either cable, bad port slot or connector, wrong cable with only 4 wires instead of full 8 wiring, wrong setting to limit to 100M.
Look inside WAN port, is one pin not parallel up like the others?

YOU ARE A GENIUS
RESOLVED: bad (old) patch cable

 

[ApexRon]

The key to your issue is the reported speed of the physical Ethernet connection between the ASUS router and ARRIS SB82000 modem. It should be 1Gbps period.

This is a physical issue for which the most common failing components are usually:

1. Cables and their connectors
2. Hardware (modem or router)
3. Auto-negotiation incompatibility

You have tried multiple cables known to connect at 1Gbps with devices other than router. Modem connects at 1Gbps to devices other than ASUS router. I am going to suggest #3 is cause. Please try a modem other than Arris, perhaps a Netgear and see if a 1Gbps can be attained.

 

[Marc Hertz]

RESOLVED: bad (old) patch cable