Check the case sensitivity parameters on your NAS. Did you made changes from the default?
Mine is working fine and I am sure lots of users are using SMB shares too without issue.
Check these settings on your SMB server:
case sensitive = True
default case = lower
preserve case = yes
short preserve case = yes
Please around with them but AFAIK, my SMB has been working fine for the last 10 years. I don’t remember what is the settings I am using on mine. I will do a quick check later once I get home.