Time Machine cannot see backup drive
Up until February 2022, I was using a Time Capsule for my Time Machine backups, as part of a full Apple Loop, from my computer to my network (iMac to AirPort Extreme network to Time Capsule) until the HD on the Time Capsule went kaput. Since Apple doesn't make Time Capsules anymore, I went and purchased a Seagate 8TB Backup Plus hub. Everything worked fine again, until the AirPort Extreme went kaput in August. Since Apple doesn't make AirPort Extremes anymore, I went a bought a pair of Asus AX6600 routers to make a new network. So while all my Apple computers are able to connect to the new network through the Asus routers, none of my Apple computers see the Seagate backup drive, even though it's plugged directly into one of the Asus routers. I tried searching online for a solve, but I can't figure it out for the life of me.
Any assistance would be greatly appreciated. Thank you.
iMac (24-inch, M1, 2021, 2 ports)