Monitor WAN service quality

Just upgraded to symetrical gigabit ethernet. Now, I’m experienceing minor outages where streams buffer and connectivity goes away. Trying to troubleshoot if it is the CAT 6 cable to the fiber converter, or if it’s an actual issue with the fiber provider.
Some information: The W1 port is syncing at 2.5 GB, the fiber is providing 1 GB. If I run speed test on the router, I get consistant gigabit speeds.

With the same configuration, but using a 500mb feed from a cable modem, I was not having any issues.

What’s the best way to troubleshoot using the Route10?

Thanks,

Kelly