I've used Foscam/Amcrest wifi cams on their own vlan with no outside access with zoneminder for years.
I have it setup to record 30 seconds of motion to my local drive.
For outside access I just vpn in. They are tied to my Homeassistant but can be viewed many different, all free and no cloud access, ways.
Any questions just ask.
Could you get a different router as others have said? It would certainly give you more options.
I use a ubiquiti edgerouter lite and use either wireguard or the built in l2pp vpn, both on the router itself.