Try all local interfaces to establish the relay connection

[flub]

When trying to establishing a connection to the relay server we just ask the OS to do it's thing and select a local interface. The OS will often pick what it thinks is the "best" interface, but this does not always works: E.g. on a phone you could have a working mobile interface and a wifi stuck in a captive portal and the OS might still choose the wifi interface resulting in no relay connection.

Instead we could employ some strategy to connect from the different local interfaces available so that a relay connection is established as long as there is one interface with connectivity.