T3 timeout then internet reboots

I get T3 timeouts 1 to 5 times a day.  All different times.  They have replaced the line to the house. New everything from the pole to the router.

Even tried using a cox modem. I have a arris sb8200 on the gigabit plan

Tried an amp booster didn't help.

Speed and readings on the modem are all normal but it still drops.

Help!