Cannot start playing - you are currently offline

Hello friends, I use a filtered internet provider where I am now and it works using the WHITELIST method. We were able to locate all the connections required to connect to the BATTLE NET and Hearthstone servers, but when I try to start a game I encounter an error message that I am currently OFFLINE and does not allow me to start a game. We tried to check if there is an additional address that is blocked by our filtering servers, but we did not see anything special.
I would appreciate it if you could help me
A. If there is a list of known addresses and ports that need to be confirmed.
B. If another cause of the above error message is known

thanks