Arcadyan KVD21

If you have a WIFI extender link that to the T-Mobile gateway and then connect your cameras to the extender WIFI. It often depends upon the age of the camera but also really comes down to the wireless channel(s) the cameras function with. The security also is a major factor as well. Older cameras often only do WPA and do not support WPA2/WPA3. 

If you suspect the WIFI signal to be weak on the front of the house and have an Android phone download one of the free wireless scanner apps and check signal strength. If the location of the T-Mobile gateway had to be moved to obtain better cellular reception the wireless signal may be weak where the cameras are. The extender should resolve a weak signal and if it is also some issue with the authentication then it may help there as well. Look up the model of the camera for specifications and find out the wireless channel limitations and also the authentication for the wireless. Check the configuration of the gateway for the authentication on the 2.4 GHz frequency and see if it is WPA/WPA2/WPA3. If the camera only supports WPA and it is not there that could well be the reason for the reference for MAC filtering. The reporting may not actually reflect quite what is going on.

If you have the Arcadyan gateway: http://192.168.12.1/TMI/v1/gateway?get=all

Use a browser and get the information about the router configuration. I believe that should also get the wifi information for authentication. I don't have the Arcadyan to know for sure but I got that from the Nater Tater videos. That is another resource you should consider. Nater Tater's YouTube videos which could be helpful as he provides a considerable amount of information from first hand experience with the T-Mobile gateways.