Mail merge with a fully qualified data source

Hello

I have a mail merge issue in Word (version O365, 2016,...) when I use a data source (.dif) on a network location with a fully qualified name (FQDN) (for example: \\mySRV.domain.lan\...). Selecting the data source returns an error and loops. If I use the short name (e.g. \\mySRV\...), I don't have the problem.

Is there a workaround (settings, registry key,...) to be able to use the FDQN name on my local network?