Specific application not being allowed through firewall even after setting up application rules

My accounting application which has a gatewayserver.exe is not getting through the firewall and the application sends a message that gatewayserver is not found. This is even after creating the rule. This was working fine till last week and for the last three days it is not working. There was not updation to my windows 10 since the service support is getting closed for the version which was installed. There has been no change to any other application including AVG. I have tried everything as suggested by the AVG and even they accessed my system but not get it through and it has been escalated. I am waiting for the solution. Presently what I do is to disable the firewall of avg whenever I need to access my application or I have to disconnect the WI-fi and then use the application.

Hi Subramanian,

We regret the inconvenience caused.
We've checked and your request has been escalated to our higher level support.
They'll get back to you via email as soon as possible.
Your patience is appreciated.