Network Connectivity, File access/Printer drop out & DNS resolution

I have a client with the following configuration:

Azure Server infrastructure
Customer DC x1
Customer Apps x1
Customer File and print x1

The Azure infrastructure is connected directly to the client site using a VPN between the gateway and local WatchGuard devices in HA configuration, the Client is running a 100mb internet link. The client site has DHCP deployed via the WatchGuard units and a DNS server has been added locally (secondary, Server 2008) to remove potential local DNS related lookup issues.

The Issue:
Local Users have connectivity issues to the following:
Printers - within the Windows 7 computers the printers become Grey and go off line (not all users at the same time)
Mapped Drives - Users experience Mapped drives going offline, a reboot/logoff usually resolves
File Access - Files Open in Read only, open by "Another User"

I need to Nail down the location of the problem to ensure i pull the right support in to trouble shoot. I need to identify potential areas in the following to get the correct support on the phone:
Watchguard, would there be any logging here or could i set this up
Microsoft Can i see anything from the server side that could iondicate and OS issues
Microsoft Azure - could this be a connectivity issue via gateway etc.

As you can imagine everyone blames everyone else so i would like to tie this down to a supplier AND/OR have some additional troubleshooting steps that might allow me to resolve the issue internally.

Many thanks
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ncomperAuthor Commented:
The following registry chain was created after Microsoft:

reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\lanmanserver\parameters /v DisableLeasing /t REG_DWORD /d 1 /f

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Network Analysis

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