Your signal levels are fine. The Signal to Noise is within spec, but at the lower end of the desired range. The question is, why are the uncorrected errors so high? I’d reboot and see what the uncorrected errors are at the end of an hour and report back. Also, what are you seeing in the Event Log? Any T3/T4 Timeouts? Any CMTS warnings? Don’t post any internal MAC information if you post a screen shot.

Additionally, to get a good speed check, connect your PC directly to the SB8200 using ethernet. Reboot the SB8200, and run the Ookla Speedtest locally, not in a Chrome or Edge browser window. Let us know what kind of speed results you get that way.

Thanks for your assistance on this.  Ran two speed tests, one direct from modem to computer and another using the ISP’s speed test via browser.  Ookla showed 40 Mbps down, 4.87 up.  ISP showed 34 down, 1 Mbps up.  My service should be 1100 Mbps down and 11 Mbps up.  Yesterday, the event log showed no events, but today, after modem reboot, there are many.  See screenshots.  ISP is scheduled to come out tomorrow.  Really would like to resolve this.

The T3 timeouts show there is a definite communication error between your modem and the Cable Modem Termination System (CMTS). You have other errors occuring as well that indicate connection stability issues. Once your ISP addresses the connection, I’d do a hard reset of the unit (with cable disconnected) and then connect and test again.

You have a ton of errors in your line and your logs indicate the same. 

Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
If you can, simply connect the modem right where the coax comes into the home. This prevents wiring in the home from being the issue. And some ISP’s charge if the wiring issue is in the home. So this helps prevent this.

If these don’t help, the ISP needs to check the line. 

ISP had equipment in our neighborhood that was bad. Once replaced speeds are back to normal. 

Thanks for the update! Thought that might be the case.