Great news, @aufdenkampe! Thanks to you and your team.
I ran a test overnight, with a Mayfly sampling every 5 minutes. Out of 179 samples sent to MMW, only one received Response Code 504, at 04:30 MST, Aug 7th. All other POST messages received successful response codes (201). The 04:30 point did not get saved to the MMW database. What I’ve observed in the past was that the ‘504’ points still got saved in the database. In any case, this appears to be an improvement compared to my previous tracking of 504 errors.
There were 4 other sample points during my test which the Mayfly saved to the SD card but apparently never attempted to send to MMW, as there were no “Sending data” nor “POST” messages in the log at those times. I believe this is a Mayfly/Xbee3 issue, not a MMW issue. I’ve only seen it when using an LTE modem, not when using WiFi.