I think you are running into some weirdness of the CommandTimeout property, as described in msdn.

The CommandTimeout setting on a Connection object has no effect on the CommandTimeout setting on a Command object on the same Connection; that is, the Command object's CommandTimeout property does not inherit the value of the Connection object's CommandTimeout value.

I suggest you create a command object, assign the Connecttimeout to the command, then execute the SQL from there.
See this VBA discussion of the failure of CommandTiemout.