Hi Pete,
It is not recommended to disable Windows Filtering Platform, because
it is a set of API and system services that provide a platform for creating network filtering applications, for example, Windows Firewall with Advanced Security (WFAS) is implemented using WFP.
According to your description, legitimate packets are blocked, I suspect it is caused by firewall rule configuration. Please enable firewall logging to find out which rule has been blocking these packets. Once found, disable the rule.
More information for you:
Step 8: Enabling Firewall Logging
https://technet.microsoft.com/en-us/library/cc754451%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396
Windows Server 2008 R2 Firewall does not log dropped packets from a Block / Deny Rule
https://social.technet.microsoft.com/Forums/en-US/147b6f6b-759a-40d6-a46f-b79329b73b91/windows-server-2008-r2-firewall-does-not-log-dropped-packets-from-a-block-deny-rule?forum=winserversecurity
Windows Filtering Platform
https://technet.microsoft.com/en-us/windowsserver/aa366510%28v=vs.100%29.aspx?f=255&MSPPError=-2147217396
Best Regards,
Amy