Lets use a common nomenclature here.
- Link = ethernet, mobile
- Connection = TCP etc.
A TCP connection works over a link, meaning a broken TCP connection cannot take down a link, but the opposite is true.
If a link goes down, the TCP connection will, since there's a timeout, be stale until the timout is passed. So check for a link lost, close the TCP connection, check if we have a working link and open up a new connection.