Automatically choosing a network interface
 

I have a machine with Mint Linux 17.3. The machine has both ethernet and wifi, both connected to my router. In case the wifi or ethernet gets disconnected for whatever reason, I'd like it to automatically use the other connection. I run a couple servers on the machine (one being Plex media server), and I'd like them to be accessible even if one network connection gets disconnected. Is that possible?

I'm asking because I'm using powerline ethernet adapters to connect rhis machine to my router via ethernet. I also put a wifi adapter in it as an alternate way to connect to my router. Sometimes the powerline ethernet adapters have a hard time talking to each other. Hence, I'd like the machine to automatically switch which connection it uses if, for example, it can't connect to the internet with one of the connections.

The wifi adapter is connected to my router, but when the ethernet connection is having trouble, I can't connect anywhere on the internet. I'd think it would be able to see that it has a connection via wifi and use that automatically?

Alternately, I suppose I could just use wifi. I'm curious how to configure Plex to bind to the wifi connection rather than ethernet, or if it should be able to automatically use either one.

NetworkManager?

It might be possible to router or fallback or assign nic's directly but a few programs.

I'd assume that the lan is selected over the wan always based on it's default metric value. You could either set the lan slower than the wan and it might adjust the metric value or you can re-assign the wan to a faster or lower number metric. Some of the metric tables have been off over the years.