Hi @stevedb,
The issue seems to be the delay inside the serial port transmission section of the code. I have increased the delay and updated the Seeed_Arduino_rpcUnified library. You can check the commit below.
I have also tested with the AdvancedWebServer example and it seems to be stable for over an hour.
Please update the Seeed_Arduino_rpcUnified library and run the demo code again.
Best Regards,
Lakshantha