Gigablast speed degradation

I've had tech's come out more than once for connection issues. 

Originally I was told my signal was too high and that was causing issues. A different time "everything was normal" when the tech came out. And yet again I'm having heavy speed degradation. 

From my modem I am seeing regular T3's

12:12:52 Thu Feb 21 2019		Critical (3)		Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4f:1d:2f;CMTS-MAC=00:a2:89:d0:1c:eb;CM-QOS=1.1;CM-VER=3.1;

But honestly that doesn't mean much to me other than I know it's a potential issue.

On the downstream bonded channels I'm showing 39.8dB to 42dB and upstream is 48dB to 50gB but again none of that honestly means anything to me specifically.

What I do know is that from my router I see absolutely zero issues. No packet collisions or loss, internally everything is flying so I am fairly confident I don't have an issue from that side of things. From the modem out however I don't know where the issue might be. Is it a COX issue or a ME issue. The cable line comes in and goes directly to the modem so I can't imagine there's anything on my end that would be the issue, but again I don't know. Currently I'm getting about 168 Mbps down and 1.55 Mbps up. At other times when things are working normally I'm a lot closer to 850-900 down and 30-35 up.

Any pointers on what to check or where to go from here would be appreciated.