Time Capsule on Orbi?

Same boat here, August 4, 20222; after my years-old Airport Extreme Time Machine failed more often in back up and the home Wi-Fi become shaky (judging a Comcast neighborhood shared) ISP and Modem, I installed the ORBI RBR750. It is super fast, which so far solves one problem. After several trial and errors, I have left my old Airport TM network in place and run it parallel with the ORBI Wifi. I use a small switch to share the cable from the modem to both ORBI and Airport. I seem to be getting TM backups, but of course there is the long standing issues of the TM management software for Apple OSx, both Intel silicon and newer Apple silicon. Sometimes the IOS Airport Utility succeeds better than AP Utility on Macbooks. I like the time machine, and the faster ORBI. The future in unclear and I will keep tinkering. I want to keep on using the build in HD and the APExtremeTC and I have one external drive too. Apple, it seems, wants us to use iCloud.