KDE Connect detects phones but won't detect other computers

I have two desktop with Kubuntu and one smartphone, all are equipped with kdeconnect.

Until Kubuntu 20.04 all devices were paired and each one could see the other.

Since Kubuntu 20.10, desktops can see the smartphone, the smartphone can see both the desktops, but one desktop can't see the other desktop and vice-versa.

I tried to purge kdeconnect, same result.

One curious thing: if I try to search for new devices from one desktop, it seems to find the other one, as for an instant its name shows in the list, but it disappears immediately!

EDIT:

I'm able to pair two desktop (Kubuntu 20.10 - let's say PC1 and Kubuntu 20.04 - let's say PC2) in my Home network. When I go to my company network, I can't pair my desktop PC1 (same as above) with another Kubuntu 20.10 (let's say PC3). No firewall on both PC1 and PC3, no firewall on the Network. On the same Company Network, PC1 and PC3 paired correctly until Kubuntu 20.04.