M32C and s32 stopped syncing

[JH3]

At random my M32C and s32 stopped syncing.

No settings have changed. Worked fine up until yesterday. DID sync on 2 power cycles out of maybe 50 tries.

Cat5 is ok.
M32C syncs fine with a different s32
Sync: INT
Rate: 48k

Tried different circuits for power. Firmware is updated on M32C but have no means to update on the s32 since its windows only.
I dont believe its a firmware issue as they both worked fine for years.

Any other ideas how to make this work properly again?