Sorry, failed to connect to multiplayer services. Server certificate authentication failed

To anyone experiencing this issue. I uninstalled and reinstalled the game and now it works flawlessly.

I still have the 0xffffffff problem. Is there a solution for this? i am using windows 11
Ekran görĂŒntĂŒsĂŒ 2023-06-10 165955

I have the exact same issue, cannot connect to multiplayer services in AoE II DE, same inside of Return of Rome mode. Am I the only one having this issue? I tried verifying my game files with Steam. Before this started happening, an update to the game was applied by Steam.

I also tried changing the computer’s date to one week ago (last time I played an online game without issues), but that did not help.

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Some of my friends have same issue. Several game updates so far this year have brought so many annoying network issues.

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Are you using a third party firewall?

I am not using a firewall in my computer, but the network I use might have a firewall
 and I have no control over that network. Do you know how to diagnostic the connection to the multiplayer services? I want to identify if something is being blocked, either by the network administrators or the ISP.

I tested using the LTE connection of my phone (via wi-fi personal hotspot), using that connection I can connect to multiplayer services
 but I don’t have a big data plan in order to use it to play continuously.

I think that accesising your router to check if there is a firewall enabled could be an option. But the easiest way could be to call your ISP and ask them.

Thanks @Felizon89 . If I call the ISP, what are the necessary details for them to open the connection? Like domain names/IP addresses of the servers, protocols (TCP or UDP) and ports that are needed to connect?

Interestingly I can connect to play multiplayer with AoE III DE and AoE IV.