As mentioned before, many times and by many posters, this is very likely a "
landlord has total control over the router" issue. I've heard little or no reports from other users having to reboot their ATV 4K on a weekly basis to get enough bandwidth through Wi-Fi to stream. A consistent 25 Mbps speed is sufficient for even 4K TV streaming. If you are getting up to 180+ Mbps speed but having it drop far down to 1 to 5 Mbps, that is in all likelihood an issue with the router. The best solution would be to keep annoying the landlord until he gives in and allows you to run an ethernet line from the router to the ATV 4K.
If he won't allow that, then explore using a powerline ethernet adapter. These have two small adapters that plug into an AC wall socket. Plug one adapter in near the router and run an ethernet cable from the router to the power adapter. No need to run a cable through walls or anything. Plug the other power adapter in near your ATV 4K and run an ethernet cable from it to the ATV 4K. The two powerline ethernet adapter units use the power lines to transmit through rather than antennas, so they should receive better than the small Wi-Fi antenna built into the ATV 4K. Here is
one example I found on Amazon. Do some research and see if you can find a good model to buy. Buying from Amazon you have plenty of time to return it if it doesn't work, no questions asked. Note: I haven't tried these, but it sounds like it might be a solution.