I checked that setting, appears to be correctly set.
And to add more confusion, I tried another iPad and it was able to find the IP address, and connect without a problem.
The working iPad: iPad Pro 11in gen2 with iPadOS 14.7.1
None working iPad: iPad Pro 12.9in gen2 with iPadOS 15.0 beta6
The none-working iPad is able to discover the windows device with other apps, and manually adding IP in spacedesk always stuck at IP validation.
Both of them are running Spacedesk version 1.0.44
