RoboRIO Connection Issue, COMM LED green even when ethernet & usb cables are unplugged

Our rbr (not rbr 2) performed very weirdly. Almost every time we powered it up, it would disconnect after a random time period (~several hundred seconds). This would also happen when the robot was kept disabled. We already switched roborios and flashed the image and firmware of these rbrs, but those didn’t work. When it was disconnected, the COMM led on the rbr kept green, even when we later unplugged the ethernet and USB cables. The only solution we had so far was to reboot it physically. It seemed like the rbrs were stuck in some mysterious state. Btw, the ds could connect to the radio in this state, but just not the rbr. It didn’t happen in the past seasons.

Since we changed rbrs, we thought this might be a program issue (from the codes). However, there were no crash information. We suspected that this might be due to full memory on the rbr, but we couldn’t confirm because sometimes it just disconnected when the last log in DS said that there’re ~50MB of memory left. Are there any suggestions? including ways to confirm the memory usage? Thank you so much!

Take a look here: Known Issues — FIRST Robotics Competition documentation
If you are using the onboard I2C (physically connected to something or trying to read/write to it in the code) it may explain the system lockups you are experiencing.

Thank you so much for your reply! I will have a test tmr and see if that’s the case.