Looks that with the recent update to version 7.8.1 Infuse on AppleTV broke access to user/password specific SMB shares. Connecting to SMB servers with user and password gives error: “username and password combination not right”.
Guest access continues to work without issues.
What type of device are you connecting to?
Can you check to ensure the username/password saved in Infuse is still correct?
If the issue persists, please send in a quick report from your device (and post the code here) so we can take a deeper look at what may be going on.