No, that is not your problem.
Possible reasons for this error could include:
Incorrect credentials (username/password) provided for accessing the CIFS share.
Insufficient permissions to access the CIFS share from the system where the error occurred.
Network connectivity issues preventing access to the CIFS share.
Misconfiguration of the mount command or options used for mounting the CIFS share.
I don't think 2 or 3 apply because UD shows the remote share as being online and available. 4 is not an issue.
That leaves 1 - credentials. Several things to look for:
Use UD to search the server and select the correct server from the drop down. Don't enter the IP address.
Let UD search for the remote server shares after entering the credentials in UD. If UD does not list the shares, the credentials are an issue,
Watch out for special characters. They can cause php issues.
Choose the share from the drop down. Don't enter it.
You can't use the 'root' user credentials.
You are probably overthinking this issue. Let UD work out the details for you. Let it find the server and the share for you and use what it finds.