Cannot see Minimserver anymore for UPNP/DLNA

[streamer99]

Thank you but your proposed solution is not very practical as these files have been copied over a long period of time and the original files are not retained. Cannot the invalid character symbols be edited to something innocuous (accepting that this may result in some corruption of filesnames?
The solution also does not address the question of why the problem has become much worse recently (there has been relatively little recent change to the files on the NAS).