Thirsty - good thought, but I'm not convinced the iPad would get as far as trying to input a password for the wifi network if it wasn't able to access it at all due to wrong frequency, as it simply wouldn't be aware of it.
Suggestion from Apple support:
If you're using iOS or iPadOS 14 or earlier, tap Settings > General > Reset > Reset Network Settings.
This also resets Wi-Fi networks and passwords, cellular settings, and VPN and APN settings that you've used before.