@Sunshine I am in a similar predicament.

I have roughly 40 IP-based wildlife and security cameras. Rather than use the native DDNS and Apps, I've turned off these "phone home" routines and access them all with RTSP streams on my LAN via their own IP addresses. In order to access them from outsuide my LAN, I have allocated each camera a bank of ports - and ran out of space as my cameras fleet hit 32.

To overcome this temporarily I have put a WISP router in the feed to a dozen of my cameras which are on a separate subnode and forwearded as individual port banks in the WISP router, but as a job lot in the main router (from the WISP router's host address). However, this is far from ideal and complicates things unnecessarily - would prefer a native DSL router that allowed 64 port forwards. Is there such an animal, or can one be flashed to achieve it, please?