when you have 2 wired internet lines - primary(fast) and backup(slower)

Hi, would it be possible to implement internet backup from another wired port too, something like: set up primary WAN port and secondary, if internet on primary becomes unavailable switch to...

@David-TP Internet-backup is indeed wonderful and long-awaited feature! But it would be even more cool, if it would be possible to use another WAN port as backup too: set up primary WAN port and...