How to Create a "Listen" Server

This guide is for those wishing to create a server rapidly without having to make a dedicated server. (Listen Server)
"LAN servers are restricted to local clients (class C)" Fix

Setting up your server

This guide is for those of you wishing to make a fully working No More Room in Hell listen server.
Many of you may have noticed all those "LAN servers are restricted to local clients (class C)" errors. It only means that those people simply clicked on "Create Server" and expected their server to work. Well, it's not that easy when it comes to the source engine. It's actually just the source engine that sets all listen servers as Local Servers by default.

First of all, before you launch your game, you will have to:

Right click on the game on your steam library and click "Properties". Once you're there, click on "Set Launch Options". An empty caption box will show up. In it, simply type: -console

Launch the game.

You will notice that a console has now appeared on the main menu. Keep it there (You can also pop it up when needed by pressing ~ )

Create a server.

Once you're in-game press escape or ~ to see the console.

Type in:

• sv_lan 0 <Press Enter>
  
• heartbeat <Press Enter>
  
• changelevel <the map you want> <Press Enter>

If it still doesn't work or you're having other issues see the troubleshooting section bellow.

There you go! You have a fully working server now! Invite your friends in!
Keep in mind that you'll have to enter those commands in the console everytime you create a Listen Server.

Have a safe zombie hunting >:)
For more information visit: http://www.nomoreroominhell.com/wiki/Listen_Server_Setup

Troubleshooting

Anti-virus and Firewalls
If your friends still cannot join your server even after you've set it up properly it's most likely because something is blocking network traffic coming from outside. Many anti-virus and firewalls do that by default and you'll have to either disable them or add Steam and No More Room in Hell to the restrictions. It's also possible that such applications (like Windows Defender) are not just blocking network traffic for your games but also ports in general. In which case you have to make sure the right ports are open as well. (see following section to know which ones)

Port Forwarding
You might also have to set-up open ports on your router. If you don't know how you just have to follow the instructions on this website http://portforward.com/english/routers/port_forwarding/
There you simply have to enter your router's brand and model and then ports for what game you want to forward. For no more room in hell it's only the port for the Steam Server.
(port: 27015 UDP)
If it still doesn't work you might want to try these ports too
UDP 1200
UDP 27000 to 27015
UDP 27020
TCP 27030 to 27039
TCP 27015

Useful Port Tester to verify if your ports opened correctly: http://www.yougetsignal.com/tools/open-ports/ Don't put too much trust on this one though.. (Thanks to Xendrid for this link)

Server not listed in the server browser
If your server or a friend's server is not showing up in the server browser you/they might want to try to connect using the console. You/They will need to type "What is my IP" on google or click on this http://www.whatismyip.com/ to find out what your/their IP address is. To connect to a server using an IP address you simply have to open the console and type: connect <IP address here>

Very High Ping from Players
Keep in mind that No More Room in Hell is a very demending game in terms of bandwidth. Many people cannot run a server with more than 4 players in it. It's easy to know how many players you can support. If you go above your limit all the other players in your server will see their ping increased to extreme heights. You just have to test how many players your network can handle.
You can also use these console commands to reduce the strain on your server:

• rate 60000
  
• cl_cmdrate 30
  
• cl_updaterate 30

Developer Update

The official game dev posted this updated information:
"As of version 1.12.3, typing commands "sv_lan 0", "heartbeat", and "changelevel" isn't necessary anymore - listen servers will now always be public if "LAN only" is unchecked in server configuration. Also, forwarding ports outside NMRiH's range is insecure and not recommended, you'll only need to forward UDP 27015 for listen servers."

[Kaede]

@Stranger I think it should do it on it's own if players allow custom addons but it tends to be really slow without a proper dedicated server with a FastDL setup. It might not even work for certain files. SorryI can't help more on this

[Stranger]

Is that possible to force joining players to download host installed addons?

[LolCat]

you deserve a lot more

[LolCat]

thank you so much

[LolCat]

this f*cking helps me with every single multiplayer game in existence

[Raz]

i cant invite my friend, i've got no clue what to do, what do i do, please help

[Gaming God]

my friend joins but it keeps saying "server full" when he joins

[Killochris]

Still can't get it to work getting error saying disconnected after 4 retries

[Felis]

FYI: As of version 1.12.3, typing commands "sv_lan 0", "heartbeat", and "changelevel" isn't necessary anymore - listen servers will now always be public if "LAN only" is unchecked in server configuration. Also, forwarding ports outside NMRiH's range is insecure and not recommended, you'll only need to forward UDP 27015 for listen servers.

[Airborne]

I can get people to connect to me using console commands but I still want it to show up in the browser. Wish I knew why it isn't.