I have SharePoint 2019 farm (Two app servers internally and two web servers and OOS server in DMZ) and opened all necessary ports for firewall changes. Web application is working internally and externally and the OOS discovery site is loading both internal and external.
But the problem is opening documents in browser and getting error "Sorry, there was a problem and we can't open this document. If this happens again, try opening the document in Microsoft Word and with some seesion id: "
Getting the unexpected errors in OOS ULS logs:
System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send.
System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
Tried to dig into this and over internet also, there is no clue on fixing this issue. Getting this error while opening the documents both internal and external.
Can anyone help me to fix this issue please?