Can you describe your network a little? Such as:
MotioneyeOS on Pi3B+ connecting to "X" brand of NAS or PC Server or Raspbian Buster Server running SAMBA services and which versions?
THere have been a number of changes in SAMBA services over the past year or two, and it's possible that they're not all aligned.
Worse case scenario, you may have to change them all to least common denominator, or upgrade to older versions if possible.
I have an older Buffalo NAS that I have to use an older setting in Buster to connect. It's not difficult.