RT-AC68U WAN Port Not Detected as Gigabit

[journeyman]

I have an RT-AC68U (stock firmware 3.0.0.4.376_1663) attached via a short CAT5E cable to my Motorola SB6121 cable modem. The cable modem is indicating that it sees the WAN connection as 10/100 Mbit instead of Gigabit--the WAN light is flashing orange rather than blue.

I've power-cycled both as well as tried another cable. In the past, I've had the SB6121 directly attached to my computer's Gigabit network port and it flashed blue then, so the SB6121 does detect Gigabit correctly.

Is there a setting on the AC68U that I can check or set to ensure a Gigabit connection? This isn't operationally critical, since my Internet connection is only 25Mbit/5Mbit, but I want to make sure the AC68U is working properly. Thanks for any info.

 

[RMerlin]

I have an RT-AC68U (stock firmware 3.0.0.4.376_1663) attached via a short CAT5E cable to my Motorola SB6121 cable modem. The cable modem is indicating that it sees the WAN connection as 10/100 Mbit instead of Gigabit--the WAN light is flashing orange rather than blue.

I've power-cycled both as well as tried another cable. In the past, I've had the SB6121 directly attached to my computer's Gigabit network port and it flashed blue then, so the SB6121 does detect Gigabit correctly.

Is there a setting on the AC68U that I can check or set to ensure a Gigabit connection? This isn't operationally critical, since my Internet connection is only 25Mbit/5Mbit, but I want to make sure the AC68U is working properly. Thanks for any info.

This seems to be a common problem with that specific Motorola modem. Do a forum search on the model number, I don't remember if users eventually found a solution, or it was a limitation of the modem itself.

 

[journeyman]

This seems to be a common problem with that specific Motorola modem. Do a forum search on the model number, I don't remember if users eventually found a solution, or it was a limitation of the modem itself.

Thanks much for the information. I found a couple threads related to Gigabit connections to the SB6121 and SB6141 where there were similar problems. The most promising one seems to indicate that, though CAT5E cables between router and modem work for some, a CAT6 cable fixed the problem for a person where CAT5E achieved Gigabit with one ASUS router but not a newer, AC one.

I ordered a few CAT6 cables and will see if that fixes the problem for me and will post back either way.

 

[journeyman]

The CAT6 cable came in today and fixed the problem. The SB6121 is detecting the Gigabit link now. It's a strange issue, since CAT5e should support Gigabit. Ah, well. Life is full of mysteries.

 

[RMerlin]

The CAT6 cable came in today and fixed the problem. The SB6121 is detecting the Gigabit link now. It's a strange issue, since CAT5e should support Gigabit. Ah, well. Life is full of mysteries.

Ethernet cables aren't all created equal. Some pretty shady cables get no real testing by their manufacturers, so they might not be totally up to specs.

 

[KGB7]

Ethernet cables aren't all created equal. Some pretty shady cables get no real testing by their manufacturers, so they might not be totally up to specs.

Yup.


A proper shielded cable should be thick as an iron rod. Cheap cables are soft as a drinking sraw.