It sounds like RA3 isn't launching correctly.
Did you make sure to:
1.) make sure it's hooked then close c&c launcher
2.) Launch from wherever you generically start the game
3.) launch it from the c&c online launcher that pops up
#Red Alert 3 Connection Error
amber violet
If you're launching it from steam, I found launching the c&c application without it requiring admin priority to start sometimes helps steam launch it.
sleek basalt
solved it, thank you Jacmac!