I recently bought a used Oplab module which came with a 5-pin MIDI cable. After using it, I noticed that the MIDI connection is not stable at all times for both MIDI in and MIDI out. Sometimes it passes the signal, while other times it does not, and there are instances when it stops during playback. It seems to me that the settings on the external devices (such as Digitone or Eurorack) are properly configured. Is it possible that the MIDI cable is causing the issue, or is there something else that I might be missing? Any help would be much appreciated."
if its v.1 of the oplab they sometimes don’t press against the metal contacts fully. Some people put a small folded piece of paper wedged in there to keep correct contact.
if its v.2 oplab it should have a little screw thingy that you can engage to keep it secure.
thats my best guess. Otherwise yeah your cable is prob crap