When an SD card goes bad it means that would operations stop working. Not all write operations fail and lots of weird behavior can result. For example logrotate sis working and your files grow and grow until you fill your card. You deleted a file and on a reboot the file comes back. You make a change to a file and save it but the file doesn’t change.
Now lots of services depend upon writing to files to work so these write fails can cause then to stop working. I don’t know if networking is one of them.
So I would test it a fresh openhabian on a new SD card and see if your network remains flakey. If not it is most likely the SD card.