So I have 2 Outdoor Cams and 3 indoor cams in my Camera group on my iPhone 13. I noticed that I could not connect to either of the outdoor cams but the others were fine. I tried the basic troubleshooting steps but no joy.
A redditor mentioned that he had luck by removing the camera group all together. I removed just my outdoor cams and was successfully able to connect to them both each individually.
iOS, Basestation and cams all had the latest firmware. FWIW.
Hope this helps!