Central Wireless AP Use with Internet Outages

Hello,

Currently have a bunch of APX units being managed using Sophos XGS firewalls and haven't made the jump to Central Wireless.

One of my larger clients has their APs deployed on their factory floor and perform nightly manufacturing. The switches powering the APs and the XGS have redundant power with redundant UPSes but the Internet uplink isn't currently redundant (working on it) and doesn't impact nightly operations.

If I move the APX units to Central Wireless and the Internet link is taken offline by the ISP for routine maintenance (can be 2-3 minutes, but can also be 2-4 hours depending on maintenance), what impact will this have on the APX units providing WiFi coverage in the factory? Will they keep providing WiFi access or will they eventually see lack of controller connectivity and go into cyclic reboot until a controller is found?

Tried looking for this information in the docs and by searching the forums but coming up a blank for an answer to this question.