What model router and switch do you have? Have you tested direct to the modem with ethernet? Your signal levels are great and you have 2 downstream OFDM channels so congestion should be less of a issue.
I have a RT-AC5300. I did connect my pc directly to the modem but it didnt obtain an ip address.
You have to power cycle the modem each time you change what it is plugged into(PC or router). If connecting to the modem is fast but through the router is limited to 300Mbps, the first thing I would do is check QoS and NAT acceleration. Looks like the router itself bottlenecks around 791Mbps as per here.
I sure appreciate what you and Darkatt do here. I remember a conversation long ago with a Cox rep on the phone. I was frustrated already because the previous person rebooted my modem remotely, even after I asked them not to, which took down the phone, so I had to get back in queue. The person said to connect directly to the modem and see if everything worked better. Nobody had mentioned power cycling before, so I didn't think the direct connection worked, plus it meant I'd lose the phone again. I vented a bit. I learned the details later, but not from Cox. Always felt a little bad once I learned the right way to do it.
It was complicated with the original phone modems(DPQ3212 I think) because they had batteries so unplugging didn't power cycle them. You had reach behind with a paper clip or something and press the tiny reboot button. So resetting remotely was part of the script. Now the FCC doesn't require battery backup so phone modems(eMTA) don't come with them. But yea, sounds like the rep. you were working with just wanted to get off the phone.
What WMO said. You have to powercycle the modem, so it see's the new system, and the server at cox knows to issue a different IP address.
I'll try that when I get home later today and post the results.
