We manage a number of pcs running Windows Server 2012 R2 on various hardware (computers have differing network cards etc.). These machines are connected at different physical locations to a physical gateway/firewall which are then connected to each other and accessed through a vpn. This setup has worked fine for years but recently the servers are intermittently and at different times losing inbound functionality, we will not be able to ping or connect on any of the ports with a running service, not just from a remote location through the vpn, but also from directly on the switch which a downed machine is connected. However outbound functionality is retained, can ping other devices behind the firewall as well as external ips. Disconnecting the ethernet jack and reconnecting resolves the issue, as does restarting the os. Windows firewall is disabled and so is windows updates. Other devices connected to the gateway/firewalls that don't run windows never lose connectivity, just the windows machines. My prime suspects are any software which is regularly updated on the machines and I plan on working through disabling that to try to prove that one of the recently updated applications is causing the issue. However, besides the possibility of a recently updated application causing issues, does anyone have any suggestions for troubleshooting this issue or similar experience on windows server?