Special public servers are not visible in the list.

[Nadolisova]

The problem has existed since November 2021. Suddenly servers that were close in location disappeared from the list. When trying to detect them, we contacted the server administrator and tried different options with his help. On the same server he raised private server on port 60606, I could connect it. But the public one was not visible and hung in “trying to connect” when connect by IP:port.
If I change network to a mobile operator, then the server was visible and available. I used a workaround several times: I connected via a mobile network to the server, and then changed it to a local one and Jamulus reconnected without problems, so we rehearsed. But since Feb 2022, this workaround suddenly stopped working. Changing server and client versions did not help.
There are no restrictions on the router. I also changed the router and it did not help. Provider has no restrictions too.

The solution was to bring up the server locally, it worked great until now. Today I didn't see him on the list, although it is in the next room within my local network. Available from the mobile network, but not available from the local network, which has no restrictions. After restarting the server, it became visible and available locally.

It’s not network or port restriction problem. Some problem is hidden in discovering servers in list inside Jamulus software.

Os tested: Ubuntu 20.04.4 LTS, Windows 11, MacOS BigSur
Jamulus tested:  3.8.1,  3.8.2. 
Server ver: 3.8.0dev-379ddf3, 3.8.2

[gene96817]

From each server, what is their IP address?
From the client perspective, what IP address is the client using to connect to the server?
What do you mean by "servers that were close in location"?
-- close as in they are a few meters apart?
-- close is in that are on the same private network?
-- something else?

I am expecting an unexpected firewall issue.
It is possible your suspicion there is a bug causing "some problem is hidden in discovering servers in list inside Jamulus software".
If true, then we need to discover what table elements from the two sever table records ("servers that were close in location") is breaking the table logic.

[pljones]

22124 is the port number your server is telling the directory it's using.

However, if Jamulus Explorer can't get a response on that port, it goes looking for a server and reports the first port it finds with a server response. That's the 51685.

You need to set your router firewall / port forwarding / related settings to understand that when you say "22124", you don't want it being changed.

[Nadolisova]

That means jamulus can change port on its own? Where i can fix it?

[gene96817]

I encountered this behavior when I was debugging my Jamulus installation. Part of that process, I was doing frequent rebooting. While you can tell Jaumulus to use port 22124, if the server is behind a firewall using NAT, if port 22124 is in use, the UDP packets will be mapped to a free port. In your case, the packets are mapped to 51685. This is the port Jamulus Explorer is seeing in your UDP packets. In this scenario, 22124 available the first time the Jamulus server starts up. On reboot, the firewall does not know about the reboot and finds a new port. Eventually the firewall will declare 22124 free.

You can fix this by defining a fixed mapping in your router.
-- set DHCP to always assign your servers MAC address the same local IP address.
-- set a fixed mapping for the firewall to always mapping localIP:22124 to the routers publicIP:22124.
-- reboot the router to flush the old states.
The result is Jamulus Explorer will always see UDP packets from your server using port 22124.
Note this only works with one server behind your firewall. You can extend the same method by assigning a fixed port (not 22124) to the second server.

[pljones]

That means jamulus can change port on its own? Where i can fix it?

That's not what I said. I said your router is changing the port and I said you need to fix your router.

[Nadolisova]

Thank you, i think i understand how it works. It expain behavior of my server. But it doesn't explain why server Geos hidden with fixed port.

I'll try some tests.