I had this problem too and just solved it for me.
In my experience Bitdefender sometimes blocks applications from accessing the internet after they got updated. Even if their firewall rule is set to allow.
That can usually be fixed by opening the list of firewall rules in Bitdefender and deleting the rule for the application in question before starting it again. In this case I deleted the rules for epicgameslauncher.exe and unrealenginelauncher.exe. The next time the launcher is started Bitdefender will recreate the rules.
Hope it works for you!