Bufferbloat(?) Network Latency Issues

Hello,

 

I am an XFinity customer experiencing significant latency issues (250+ ping and higher on uploads via DSLReports Speed Test http://www.dslreports.com/speedtest/67159599). There are not issues with downloading/streaming shows, mainly when trying to videochat, play games online, etc. Equipment is Netgear C6250-100NAS; issues are present even with a direct line ethernet cable from router to computer.

 

From what little I have been able to make sense of, 2/4 Upstream channels are 'Not Locked', and not showing any power. [Link to screenshot before mod approval for in-line pics] Dashboard screenshot here: 

 

I also have an error log chalk full of Unicast Maintenance Ranging Timeouts from this evening-- often multiple per second. [Link to screenshot before mod approval for in-line pics]

 

Not sure what I should do to fix this problem-- any advice would be appreciated.  Please let me know if there is other information I can provide to help figure out next steps.

 

Thanks,

Mike