I've had this goofy problem with my #unifi kit (original #UDM/white cylinder) where my speed drops from ~900MB to ~80MB while connected to it. I thought it was an #xfinity issue, but if I connect directly to their modem, I see the speeds I'm expecting. Sometimes rebooting the router will clear it up for a little while. Currently connecting via wifi, but I'd previously seen the same behavior on wired connections, too.

I've done some searching, but have yet to figure out the cause or a fix. Throwing this out to the nerdosphere to see if anyone has any ideas (i.e. boosts are appreciated!).