Connecting Minecraft server in different bridge

jjimenez

Occasional Visitor
Hello again :)

I don't know if this is the right place to ask this but... there we go:

I have a RT-AX58U with Asuswrt-Merlin (last version). Following a post in the forum, I created a new bridge (br100) in order to separate some devices in my LAN (those devices are exposed to the internet) and applied some iptables rules to manage traffic between bridges. My problem is that my PS5, connected via WiFi and part of br0 (my LAN bridge), can't connect to my Minecraft server, wired to my br100 (new isolated bridge). The PS5 is the only device that cannot access the Minecraft server, the rest of the devices connected also to br0 (tablets, phones, and PCs), can connect without problems.

The difference is that in all the devices, I can tell Minecraft the IP : PORT of my server, but in PS version I don't have that choice. It should appear in a tab called "Friends", which should show all servers in LAN. It works when I have my Minecraft server connected to the same bridge.

I've read somewhere, that the PS Minecraft version uses multicast to discover servers in the LAN, so my guess (being a complete noob on networking) is that the multicast is not jumping between bridges. Is it possible? I've seen in my router that there is an "Enable multicast routing" option in IPTV config, but it seems does not affect the issue. I don't even know if that option affects to the LAN or only to IPTV.

Any idea? Thanks in advance!
 

BreakingDad

Very Senior Member
Do you have upnp on , on the main router? If so and it's not working you could try port forwarding from the main router to the ps5.

Set a static ip on the main router for the ps5 in dhcp and then go to port forwarding and forward the port of the mc server to the ps5.
 

jjimenez

Occasional Visitor
Do you mean this option in WAN settings?

Captura de Pantalla 2022-07-14 a las 13.15.02.png


It is disabled. What other side effects can have that option on my LAN? Will the router open ports to the outside automatically for some of my devices?
 
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BreakingDad

Very Senior Member
Good Question. I think for anyone that plays games, has gaming servers, smart devices etc it's a necessity, that said there are flaws in it that can be exploited if your computer is not up to date and free of malware.

UPnP, therefore, is not inherently dangerous. It becomes an issue only when there are infected devices on your network.
Will it open ports - yes, but only for those that require it and only when they required it, assuming you have no infections.

You may have to turn on UPnP on the PS5 network settings as well, not sure how that console configures.

That said there is a trade off for convenience over security. Personally I have used it since it was introduced in 2011 and suffered no issues from having it on.
The other option, as referred above, is to leave it off, and port forward manually, which for me is a pain considering the amount of pc's and different games and servers on my network.
The choice is yours, I am sure plenty others will chip in with stories of when the FBI were hacked by a UPnP attack and other such horror stories. For the home users I think the risk is negligible.

I would try it on, see if the ps5 connects with it on, then you know you have a port forward to set manually if you want to proceed without uPnP


All of that said, I think your best bet would be to forward your minecraft server ip and ports to your ps5 using portforwarding.
 
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jjimenez

Occasional Visitor
Thank you very much for your explanation @BreakingDad. I will try later today what you suggested.

Just to be sure I understood the second option, when you say "forward your minecraft server ip and ports to your ps5 using portforwarding" do you mean this?

Captura de Pantalla 2022-07-14 a las 16.46.02.png


Or the opposite? Minecraft as Internal IP Address and PS5 as Source IP?

Thanks again!
 

BreakingDad

Very Senior Member

ColinTaylor

Part of the Furniture
I think that is correct, @ColinTaylor @L&LD could you verify please ?
Normally the Source IP address would be left empty. But as he has a completely non-standard bridge setup all bets are off as to whether any of the router's features will work as normal. But from what he said earlier it seems like this is a multicast detection issue and nothing to do with forwarding ports.
 

jjimenez

Occasional Visitor
I tried enabling UPnP but it didn't work. So I think the problem is about the multicast between bridges.

@ColinTaylor thanks for your answer. Any idea how can I fix this? or am I trying to do something which is simply not possible?
 

ColinTaylor

Part of the Furniture
@ColinTaylor thanks for your answer. Any idea how can I fix this? or am I trying to do something which is simply not possible?
Sorry, no idea really as I haven't looked much at custom bridge setups. You might have to manually configure the mcpd daemon.
 

BreakingDad

Very Senior Member
What is the idea behind using a separate bridge? can you not do all of this off the main router?

It seems I may have been barking up the wrong tree, I know when I had a rpi mc server, I had to port forward to get it to work, and to get clients to connect from outside the network.

Better to try and fail I guess.
 

jjimenez

Occasional Visitor
Sorry, no idea really as I haven't looked much at custom bridge setups. You might have to manually configure the mcpd daemon.
Thanks! I'll investigate that path. I've seen that file and there might be a reason for my problem.

What is the idea behind using a separate bridge? can you not do all of this off the main router?
Well, my idea was to separate in a different bridge the devices exposed to the internet, like the Minecraft server (I want someone from the outside can connect to it), and some other Linux machines (some webs or services, nothing big). So I isolated that bridge, there is no connection from br100 (where the Minecraft server is) to br0 (my LAN). I use iptables to allow specific traffic from (and only from) br0 to br100.

My idea might be correct or wrong, I'm not an expert on networking, honestly :)
 

BreakingDad

Very Senior Member
I did just do some googling and stumbled over this https://github.com/jhead/phantom

It may be of interest to you. I am sure over the weekend when the real smart guys see this thread someone will chip in. It should be simple right, to get a MC server to be picked up on a console.
 

BreakingDad

Very Senior Member

BreakingDad

Very Senior Member
This works! :) definitely my workaround for now, it does what I need :)

I took a look at the mcpd.conf file, but there is no documentation over there and I don't know if the thing I want to do is possible or not, so... phantom is good for now.

Thank you very much both of you for your answers!!
Ahh fantastic news, how did you install it (implicate it), was it on the MC server (linux/windows) or on the router/bridge/linux box or other?
 

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