[leopod]

Thanks for the suggestions, they were totally relevant with this case. Unfortunately it didn't solve my problem

Catalina doesn't seem to offer USB networking for iDevices, as they don't appear in the SystemPreferences/Network, even if they are plugged in and computer considered as "Trusted" by the iDevice.

As for the order, we have Ethernet 1 who carries internet and LAN connections, while Ethernet 2 carries the S6 network alone. So they have to stay in that order for internet to work. The rest of networking options are "Off", including Wifi.

We might have to upgrade to Big Sur and maybe iDevice handling will be better handled. In the meantime i've sent a case to Avid with log files.

Edit : I did try placing Ethernet 2 in first position for troubleshooting purposes, and same problematic behaviour occured.