Floodlight Cam in shipping container

Hi, i have a shipping container that i use as a workshop. I've a WiFi router inside the container. I've set up a Ring security system in there consisting of 1x door sensor, 2x motion sensors, 1x stick up cam, 1x base station and 1x floodlight cam. All set up perfectly and working fine with the container door open. However whenever i close the container door the floodlight cam simply goes offline, every time..., open the door and it comes online again! I called up customer support and they were insistent it's the WiFi, they just wouldn't have it that i said it can't be as the WiFi is inside the container!, it wasn't until i said the stick up cam works perfectly, door closed or door open. They are sending me a replacement floodlight, however i don't think it'll work, i think it's something else, does anyone have any suggestions?