Outdoor camera base limitations

I started out with using two of the wireless outdoor cameras each with its own base. After several months without issues I decided to purchase a two pack (two cameras with one base) and add to my system. after a few days, I began to have an issue with one of the new cameras losing connection to the base. This continued to be a problem so I purchased a fourth base station so each camera would have it's own base. Set everything back up and lost two cameras within  a couple of days again.  Moved all bases to where they were within a few feet of the cameras and tried again. Within a few (3-4) days lost two of the cameras again. A week later a third camera that had been stable earlier  dropped out. It should be noted that I can delete the cameras from the base and re-add them and they all start working again but only for a few days. At 71, it is a real pain to have to get on a ladder to re-pair the cameras. I have several indoor cameras that are without issues. Could someone please suggest something to try that might resolve the issue? Am I using too many bases on a system? Is there any restriction to quantity supported? Note that the bases are always connected to the network. It is the connection between the base and the cameras that is causing me problems.