This happens often and the only way it resolves is by deleting/adding the camera.
I have several versions of cameras and it happens with the newer ones, not the v1, v2 or outdoor.
Next time it happens try rebooting your router, then if that doesn’t work try rebooting your phone. Just helps to narrow down where the issue is. Some of the cameras use different protocols and I’m wondering if something may be getting “stuck” in your router (then when you re-add the cam, it resets it).