Adding a trusted network location in Office doesn't allow mount/drive letters. What is required is a UNC path, however this doesn't work for network drives mounted on IP address. ----------------------------------- First there is a general step to make the tick box "Allow Trusted Location on my network (not recommended)" available. This tick box is located in Office > Options > Trust Center > Trust Center Settings > Trusted Locations To be able to enable it, we have to change the registry; - Regedit (as Admin?) - Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Excel\Security\Trusted Locations - REG_DWORD "AllowNetworkLocations" = 1 - Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\Trusted Locations - REG_DWORD "AllowNetworkLocations" = 1 ----------------------------------- But now the work around for IP addresses. Go to; Control Panel -> Internet Options -> Security -> Zone : Trusted Sites Add IP Address (tick HTTPS required) without any slashes or prefix. Just the IP and press Add / Close This is it. No modifications required or location to add in office trust center.