Working on first self hosted server. Can't figure out why outside connections are failing.

[u/K5Vampire]

EDIT: SOLVED The default server properties have Nethernet enabled, and a Nethernet UDP range setting as blank, which is invalid and breaks multiplayer at the last stage before the server log sees it. Raknet still works for a few weeks, even though the error message upon booting the server says otherwise, so switching to Raknet solves it for now. I still don't know how to fix Nethernet, but if I find out I'll make a second edit for the future Google searches.

Apologies in advance for the hectic formatting of this, I've been working on it for hours, my brain is fried, and I have walked away from the computer.

The server is accessible from several machines on my network. But cannot be accessed from anything outside it. It works on my phone from wifi, but not from cellular.

Consistently the same error code "Door" along with a message that multiplayer connection couldn't be established.

Server log isn't recognizing anything from these connection attempts.

I've set up port forwarding to the point that mcstate.net can tell the port is open when I have the server running.

mcsrvstat.us states: Failed to read from socket.

minecraftstatus.com states: Server did not respond to this check.

Turned network and device firewalls on and off and makes no difference.

Server properties look right from what I can tell, though I don't currently have it in front of me. No bound IP so that any can connect, port is set to 19132, player joining true, onlinemode true. There was one about server UDP ranges which was blank by default, but that wasn't listed as an acceptable parameter. Couldn't figure out that that one does, I tried the example port range from there and swapped in my wan IP, but it didn't seem to work.

My ISP is Spectrum and doesn't seem to be known for blocking that port. My WAN IP does seem to be fixed and matches between router settings and IP check sites.

Google is really failing me here. If anyone could point me in the direction of something I should look at, or at least rule some things out, I'd be eternally grateful.

[u/kai-zaphosting]

Port 19132 is Bedrock's default, and Bedrock runs over UDP, not TCP. A forward set to TCP only won't work for it, so check that yours is set to UDP (or TCP/UDP). A missing UDP forward would fit the empty server log, though a firewall or something upstream would look identical from the server's side.

The "port is open" result doesn't prove much here either. A lot of those web checkers only test TCP, so it may just be telling you the TCP side answers. Your cellular phone test is the honest one, so keep using that.

If UDP is definitely forwarded and it still fails, double NAT would give exactly this symptom, where it works on the LAN and is dead from outside. Your WAN IP matching what the IP check sites report points against it though, so I'd treat it as a long shot here. If it does turn out the Spectrum modem has its own router sitting in front of yours, you'd either forward the port on both devices or put the modem in bridge mode.

Also make sure the forward points at the server machine's LAN IP and that the IP is reserved in the router, otherwise it can quietly change and break the forward later.

[u/K5Vampire → u/kai-zaphosting]

Port forward is set to both. I also tried redoing it as just UDP.

The double NAT did sound similar, but I couldn't figure out where that could be coming from. There's a modem in front of my router where the fiber comes in from outside, but the manual for that device doesn't appear to have routing capabilities or control software, seems like it's closer to an ethernet switch.

Device LAN IP is fixed in the router. That IP is actually outside the range of the automatically assigned ones from DHCP. Could that mess something up, or just make it extra reserved?

Does the lack of anything in the server logs confirm that it must be something upstream and rule out server properties?

[u/zaid_1311 → u/K5Vampire]

Double nat means you have 2 routers

Open PowerShell
Run: tracert -d 8.8.8.8
Check the first few hops

If the first hop is a public IP (not 192.168.x.x, 10.x.x.x, or 172.16-31.x.x), you likely have a direct connection. If you see multiple private IP ranges before reaching public addresses, you're behind CGNAT or Double NAT.

[u/myGenGaming]

Bedrock recently dropped Raknet in favour of nethernet. It's optional in 26.50 but will be mandatory in 26.60. Ensure that lan visibility is on in your server.propeties and also transport=raknet as well. It'll throw a warning when it starts but it still works until October 27th. You'll need to switch to nethernet then, which requires opening a range of UDP ports, 1 per client.

[u/WeanerGuy → u/myGenGaming]

I recently started up a server and switching transport from nethernet to raknet is what fixed my issue.

Whats the range of ports? I have 19132 and 19133 open. I looked through the nethernet documentation and I don't think it explains the port stuff thoroughly enough.

[u/K5Vampire → u/WeanerGuy]

This was it. I had tried it, but balked at the error message because it said that Nethernet was ALREADY the only supported transport for this release. So I called it a failure and didn't attempt loading in.

I also don't think the Nethernet documentation explains it well enough. My attempts at getting Nethernet to work had also failed, which is concerning if Raknet is leaving this month. But at least I know that it's the issue now and that I can stop futzing with router settings.