While I can feel @mfr476 frustration he might have with his own installations, I don't think he's right in this particular case. Software and hardware problems tend to pop up at random times (even though they tend to correlate with external issues), but if OP's problems are regular, that might indicate some external reasons.
My first thought with wireless links would be to check for interference. Which might be some other wireless link, but more probably some unrelated RF stuff which one can not detect using usual WiFi gear (it will only show high interference), but a proper RF scanner might show it. And for sure nothing will show after the link is already running again, if events occur "on schedule" you have to be on site and prepared to hunt the interferer.