Ok this is something which is really making me frustrated these days.
I really hope that this functionality will be improved in c2 and also implemented in c3.
For example in c2 multiplayer plugin i would really like to see new action called "Set host IP and port".
And would like devs to modify signaling server, so that when it is unable to provide connectivity to host / peer via STUN and TURN servers, so to issue directive to client that he should connect over IP and PORT which host provided in lobby before creating game.
I think that it would enable us to achieve 98,8% peer to host connectivity rate.
Of course host would have to make little adjustments on his router (port-forwarding maybe). But its a fix... (Hope that this is a possibility, because c2 is using WebRTC). Currently i'm in a situation to have a game which works in lan, but fails to establish peer to host connections over internet due to signalling server flaws.
Also would be nice to see Socket IO official plugin, maybe even server implementation provided by Scirra. But at least Socket IO compatible plugin that would allow users to code up their own servers and enjoy the benefits of WebSockets as a centralized server possibility which would also allow us to achieve 100% host to client connectivity (even though socket io is not bare WebSocket implementation which i assume could be a challenge for Construct devs). And again yes, you would have to pay for hosting, but who cares its a QOS that matters, and i personally as a future software vendor would not like to leave my customers without ability to play against their friends online.
That is something i would really, really like to see in c2 and ofc in c3.
About current multiplayer i like for example how multiplayer objects are made and how syncing is done (though i haven't tested it on larger scale game so far).