Two subnets should be able to communicate

[littletadpole]

"Nearly all" doesn't mean all, right? Turn the AP off, repeat the tests with the remaining devices. If this works, you know it's the AP's fault.

You are correct; however, I assume it's the AP's fault.

I've swapped OPT1 to 192.168.20.0/24 and everything is working fine now.

I highly suspect it has something to do with how orbi handles its guest network, which is hardcoded to 192.168.2.0/24. To be clear, the guest network is disabled, but I think some other things are going on under the hood causing it to treat this traffic differently.

Thanks all of you for the help, I really appreciate it.