DSM Not Responding
If a DSM has power lights but is not responding to pings, ssh, or on the bluetooth console, make sure the micro SD card has not popped out. Turn off the Pi, push in the SD card, make sure it clicks and stays in, then turn power back on.
Bad RMYoung Sonic Data
If an RMYoung is reporting occasional NANs for wind speed, check that the serial messages look clean: all lines the same length and no random characters inserted. If not clean, try ports 2-3 or 6-7.
If RMYoung messages have a non-zero diagnostic flag in the last field, then the problem may be low voltage. Some models seem to only work with around 12V or higher. If voltage is good or cannot be changed, then we don't know of any other way to fix it and it should just be replaced. Some of the ARL RMYoungs are very old and well-used.