Weird communications problem

[Peter Fletcher]

I have a weird problem with weewx on a Pi 3B that had previously  been running it happily for more than a month. Please excuse this long post, but it is difficult to know what is relevant.

I was using WiFiLogger - a reasonably new IP logger - to connect to my Vantage Pro 2 weather station. I had encountered few problems (none that were not easily sorted out) until some beta network monitoring software I was testing crashed spectacularly and left my network in a shambles. In order to sort this out, I had to shut down everything on the network, including the router and (separate) WiFi Access Point, and bring it up again from scratch (without the offending beta software!). After I had done this, everything worked normally again, but weewx appeared to be unable to communicate properly with the IP logger. I was able to confirm that the logger itself was still working and accessible at its assigned IP address, and it appeared that weewx was also able to reach it but was not receiving comprehensible responses.

In the hope of getting the weather station communications back up and running, I switched to an older, but known good, USB logger, changed weewx's settings appropriately, and restarted the program, only to see almost identical communication problems to those I had seen with the IP logger. At this point, I decided to install weewx on another Pi 3B. There were no problems with the installation and weewx ran and communicated normally with the USB logger! I am using this as a workaround for the bigger problem, for now. Going back to the original Pi, I 'purged' weewx and reinstalled it from scratch as I had on the second Pi, hoping that this would clear whatever problem may have been caused by the original network crash, but it still won't talk to the USB logger (relevant syslog record attached).

Has anyone any ideas as to where I should look next? I emphasize that the Pi on which weewx is not working properly is otherwise functioning entirely normally, with a number of service scripts monitoring other sensors and communicating normally with my Windows system over the local network