Internet dropping with new plan & equipment: Gigabit plan, Motorola MB8611 Modem, TP Link AC4000 Router

I recently upgraded to the gigabit plan and replaced my old MB7621 modem and AC1200 router with the MB8611 and AC4000. Even before that, we had a lot of multi-day outages over this summer.

Now, it seems to cut out for 10 minutes every few hours or so. It can be when I'm streaming or when I am just surfing. I also replaced the ethernet cable, the MB8611, and AC4000, and it still cuts out.

I'll try replacing the coax soon, but that looks fine. I'm in an apartment so that's the last thing I can replace. Any ideas for what else to do? Is this something for a tech appointment?