Tiberium Wars, standalone version (not bundled) purchased via steam and running on windows 10 - 5 different people and we are all experiencing the same problem in any combination of computers/players etc.
We are all loading via the CNC-Online interface, we can see each other in the lobby and join the same game and also chat in the window. When all players have selected ready and we try to start it gives this error: "Connections are in progress, or connection problem detected. Please click the Connections button where you can check every player's connection and retry"
Error Log File:
----- C&C:Online Launcher Start -----
C&C3 Install Path: C:\Program Files (x86)\Steam\steamapps\common\Command and Conquer 3 Tiberium Wars\
Started game with: ""C:\Program Files (x86)\Steam\steamapps\common\Command and Conquer 3 Tiberium Wars\CNC3.exe""
Caught CREATE_PROCESS_DEBUG_EVENT from C&C3. Detaching...
Found game.dat process. PID 1225613048
*** Starting CA public key patching routine ***
CA public key is expected value.
Successfully patched CA public key.
*** Starting hostname hooking routine ***
Injecting DLL into game.dat process...
Result of injection: Code -1073741582
NATNeg test result:
Using server nntest.cnc-online.net:30000
Bound to local port 51059
Bound to local alternate port 51060
Resolving hostname 'nntest.cnc-online.net'...
Resolved server host to be '126.96.36.199'
Sending client INIT from port 51059 to nntest.cnc-online.net:30000
Received server INIT 
Our public address is 188.8.131.52:14195
Sending client INIT2  from port 51060 to nntest.cnc-online.net:30000
Received server INIT2 
Our alternate public address is 184.108.40.206:14196
Sending cient START  from port 51060 to nntest.cnc-online.net:30000
Received server START 
Server extra port is 40000
Sending client PING  from port 51059 to nntest.cnc-online.net:40000
Received server PING(2) 
Received server PING(3) 
Received server PING(4) 
Received 3 pings from nntest.cnc-online.net:40000.
NAT negotiation works with your router and connection.
==> You do not have to use port forwarding.
Press any key to continue . . .