I'm just curious to know if this is doable with OpenWrt.
In some network firewall appliances (like those from Sophos), they have a feature called 'multipath rules' where you can specify which WAN interface to use for what kind of connection/traffice. For example, traffic destined for *.youtube.com should only use WAN interface 2 while all other traffic will use WAN interface 1.
I combed through the documentation and the closest I could find is the article for Multipath TCP, which sounds more like link aggregation than what I have in mind. I found a suggested similar article about Multiple WAN interfaces and routing but it looks more like static routes than the multipath rules I mentioned (although admittedly, it's closer than multipath TCP, just without the URL-based ruleset).
Is there anyone out there who can give inputs on this? Please advise. Thanks!