Motorola modem SB6120 not identifying gigabit router (ASUS RT-AC66U)

[MrSinatra]

I think its worthwhile to use a cat6 cable if you're experiencing issues, just to rule cabling out.

 

[F5ing]

Correct always blue. Glad someone else has one to compare.

haven't tried that yet but I thought about It, been blue since Comcast restarted it on there end so far. If it changes I'll set it to factory good idea thx
Never had an issue, bought this new router started seeing amber light! just not sure if its the router?

I'm on Cox rather than Comcast and connected to an RT-N66R rather than a RT-AC66U.

One thing I've noticed with Cox (at least with this modem) is that after I do a factory reset of it I'll see the signal levels/noise/bonding parameters improve, sometimes dramatically. Never noticed this with Cox and older modems.

I'm not sure what happens here, whether it's the cummulative effect of Cox's periodic modem updates or not. I don't recall this happening with other modems on Cox's network.

Over the years I've gone back to factory default about 5 or 6 times, but it hasn't been because of "reliable" connection problems though. It's because when I've notice degraded signals, or something "not quite right", I give a reset a try.

No clue on whether it would affect the modem's link to the router though. Just figured I'd thow out an option that can't hurt, yet might help.

 

[jhoff80]

Did you ever get this solved? I'm having the exact same issues with the SB6120 and an RT-AC66U as well.

The cables are all CAT6, and the previous router I had installed (a Buffalo WZR-1750DHP that had to be moved to purely AP-only status due to not supporting NAT loopback) gave a gigabit connection over WAN with the same cables that are being used for the RT-AC66U.

If I start the modem first, and then reboot the router, it generally gives me a gigabit connection, but then at some point it falls back to 100mbps. I realize it's not going to be too much of an issue with regards to speeds, but I'm still OCD enough to want it to be at 1000mbps (and plus, the amber light is much more annoying than the blue one).

Is there maybe any way to turn off the auto-sense and just force it to 1000mbps or something like that that I've missed? Or did the OP find some other resolution maybe?