This is not related to openSUSE, I think, but I was so puzzled I'd like to ask for help understanding it.

About one or two weeks ago kdeconnect couldn't pair my desktop (IPV4 only) and my android phone, as they couldn't see each other.

I went through all checks I could think of and suggestions found on the internet - add kdeconnect-kde service to firewall (it already was, obviously), open ports manually, turn firewall off, check journalctl, etc., to no avail.

Just on the off-chance I pinged the phone from the desktop, and to my surprise the destination host was unreachable.
Now, I have two WiFi APs, call them AP1 and AP2, and my phone is usually connected to AP1 with a fixed IP. When I moved the phone near AP2 the phone switched to it, with a new, dynamic IP, and I could ping it!

kdeconnect could then see both devices and pair them, transfer files, etc. The firewall is active, with the manually open ports removed.

Now what puzzles me is that when I moved the phone back to AP1, I magically could ping it on the fixed IP again, and kdeconnect is still connected and working! And it keeps connected after switching APs back and forth again.

Also, except for the IP, the gateway, DNS and subnet mask are the same, with randomized MAC address.

I'm at a loss to explain that, any ideas?