1) Using different patches did not help.
2) Running as administrator did not help.
3) Uninstalling all mods did not do the trick either.

I found the log file. Should I post it here, or should I send it via a pm?

hi
either is good.
i ssume you are now using windows defender. see if this makes any difference, disabling 'real-time protection,' 'cloud-delivered protection,' and 'automatic sample submission'

I have sent a pm with the Voobly log file to both sunny@voobly and kitt. If anyone else is interested in the file, feel free to ask

hi
thanks.
in your game settings in the room, do you have "disable hardware acceleration" ticked or not?

Yes, I do (and unchecking it did not solve the problem).

hi
the problem would appear to be dx related
try adding these to the firewall:
Ports

UDP 17600 to 17900 inclusive (Voobly game lobby traffic)
TCP 17600 to 17603 inclusive (Voobly instant messenger)

IP-Addresses

198.50.175.0
198.50.175.1
198.50.175.2
198.50.175.3
198.50.175.4
198.50.175.5
198.50.175.6
198.50.175.7
this may seem odd but do you have anything xp related on pc? [AppCompatFlags = WINXPSP2 RUNASADMIN HIGHDPIAWARE]
if you have used compatibility for xp, update it to xpsp3

hi
is your UAC on or off?

Adding the ports/ip adresses did not help.
I checked the compatibility mode, and saw I used xp xp2, so updated it to xp sp3, which did also not help.
My AUC is turned on.

Hi there,

I have checked the log and there is nothing suspicious out there.

You don't have to use compatibility mode, so uncheck it. You mentioned the game launches in single player mode so it is not a compatibility issue for sure.

Try hosting a game in another lobby (CS for example) and see if you have the same problem out there.

Do make sure you do not have any visual mods active. You mentioned that you uninstalled all mods. In case you got them back, make sure all visual mods are completely disabled.

Most importantly, you need to run Voobly and AOC as an administrator. This still seems like a permission issue to me.

P.S: If you are not already running aoc in window mode, please you do so.

The same problem also occurs in other lobbies. I removed all visual content mods again, but once more, this did not solve the problem. I re-checked, and both voobly and AOC are running as administrator. The game is also running in window mode.

Create a new windows Administrator profile and try again.

No difference.

Could you try connecting to a different network as opposed to your regular one. A neighbors wifi, or even better your mobile network. See if you have the same problem.

Used a different network, but the problem persists.

Well then it has to be your firewall. Somethings just not adding up. I would suggest you go through the checklist again:

1. Firewall and security apps (Uninstall all of them)
2. Login with an Admin account for windows
3. Start Voobly as an Admin and make sure the game room settings are as shown below:
[You must login to view link]
4. Run the game with different patch with and without Anticheat
5. Disable all data mods and uninstall all visual mods
6. Connect through your phone network (3G/4G)

Finally, follow the steps mentioned here to perform a clean installation of the game:
http://support.voobly.com/display/vkb/KB1019+Clean+installation+of+Age+of+Empires+II+with+the+latest+patches