recently cant access remote security camera over cellular data

I have a remote security camera system that for many years I have been able to view on my various iphone versions over cellular data.

Recently i cannot connect.  It uses port 8000 and a DNS entery to connect to the cameras.

It works fine on wifi on my phone and on my PC.

It does not connect using cellular data on my phone.  If i use my phone as a hot spot my computer cannot connect.

So clearly something on the cellular data side is preventing the connection.

Any ideas?