When you are query several servers at once, it is rather unclear
for which server you got a popup. Instead, show any errors on the
server itself.
This is only true for the query-part. Joining a server still gives
an error popup to tell you about any issue.
TURN is a last resort, used only if all other methods failed.
TURN is a relay approach to connect client and server together, where
openttd.org (by default) is the middleman.
It is very unlikely either the client or server cannot connect to
the STUN server, as they are both already connected to the Game
Coordinator. But in the odd case it does fail, estabilishing the
connection fails without any further possibility to recover.
Before 8a2da49 the NewGRF names were synchronized using UDP packets, however
those have been removed. With this a new version of the GameInfo packet is
introduced that allows to specify the type of serialisation happens for
NewGRFs. Either only the GRF ID and checksum, or those two plus the name of
the NewGRF.
On this request for local servers will send the NewGRFs names.
The Game Coordinator will get the names on the first registration, and after
that only the GRF ID and checksum.
This method doesn't require port-forwarding to be used, and works for
most common NAT routers in home setups. But, for sure it doesn't work
for all setups, and not everyone will be able to use this.
In this mode you do register to the Game Coordinator, but your
server will not show up in the public server listing. You can give
your friends the invite code of the server with which they can
join.
This removes the need to know a server IP to join it. Invite codes
are small (~7 characters) indentifiers for servers, which can be
exchanged with other players to join the servers.
OTTD_COORDINATOR_CS for the game coordinator defaults to coordinator.openttd.org:3976
OTTD_CONTENT_SERVER_CS for the content server defaults to content.openttd.org:3978
OTTD_CONTENT_MIRROR_CS for the content mirror server defaults to binaries.openttd.org:80