The correct approach to this is to totally separate the functions of "Router" (which is not a WiFi device despite common misusage to imply that it is) and "Access Point" (the WiFi Device, or devices.)
Consumer-grade "WiFi Routers" are a router (generally of no great note) in the same box with an access point, and sometimes a small switch.
You need a router of considerably more sophistication - there are many options that work, ranging from "free" to tens of thousands of dollars. I'll suggest (but note that it's only a suggestion and there are many others) pfSense as one free (software - you do need to provide a box to run it on) option which can handle multiple WAN connections.
Then you need some access points to deliver WiFi from your wired network. If you stick with "Access points" rather than "routers" you're already halfway along the road to probably getting something of better quality than most consumer junk, but "shopping questions" are not OK here (they are in chat, I believe) so I'll skip recommending a brand.