Maybe you can look at the logs also on the kodi machine. It should have too tail installed, so with a parallel ssh session, you can try to see what’s going on also over there.
EDIT: Is odroid using an SD card? If yes, maybe the card is failing and this strange behavior is an hardware problem. A 3/4 years use of an SD card as an alternative to a real disk should kill even the best brand with a wear-leveling firmware. Those mass storage device are not made to be a disk.
This explains the low port. Kodi uses libnfs to open a share and as documented on their github page the port number choice depends on the root status. Since Kodi in the large majority of cases run as a non-root user, the insecure option becomes mandatory on the server side.
This is compatible with the hypothesis of a failure in the SD card. If there is an i/o error, the filesystem is completely silent as the firmware does not report any problem. Sudden crashes or freezes is the common sign of nand flash cells failing in the SD card.