https://support.tablotv.com/hc/en-us/articles/115002622263-What-is-Maintenance-Mode
That link appears to reference the local Tablo device owned by the user being unavailable for a brief period of time if you happen to go into the Live TV grid when it is being updated on the Tablo device itself.
I apologize, I may have misunderstood your comment as you said “servers” which to me would be referring to the infrastructure/servers on the Tablo company side and didn’t know if it was accurate they went “offline” every night for the guide update.
I found if I am recording or watching the streaming channels like ION, i get a lot of playback problems. I have mine hooked up to wired Ethernet. If I was to guess, it can not stream out the recording or live TV while recording an internet channel possible due to the Ethernet load? I can successfully record OTA Live tv and watch with no problems. When it is done recording the streamed channel, I have no problem playing it back as long as the steamed recording stopped.
Sometime I also have to restart the app on my playback device.