Multicast Issues with RT-AC68U Repeater

[ryehumour]

First time merlin user here. Have been following along on the forums to try and get my RT-AC68U to broadcast multicast packets (specifically mDNS) on the both sides of the repeater.

I've turned on reflector for the avahi-daemon via /jffs/configs/avahi-daemon.conf.add

[reflector]
enable-reflector=yes

and restarted mdns via service restart_mdns (and since rebooted the router).

However, I still get different mDNS responses to discovery queries for each machine depending on which side of the repeater it's on.

Am I missing something simple here?

Thanks!

 

[drinkingbird]

First time merlin user here. Have been following along on the forums to try and get my RT-AC68U to broadcast multicast packets (specifically mDNS) on the both sides of the repeater.

I've turned on reflector for the avahi-daemon via /jffs/configs/avahi-daemon.conf.add

[reflector]
enable-reflector=yes

and restarted mdns via service restart_mdns (and since rebooted the router).

However, I still get different mDNS responses to discovery queries for each machine depending on which side of the repeater it's on.

Am I missing something simple here?

Thanks!

You should not need the reflector with repeater mode. That may actually be interfering. The reflector should only be needed when going between subnets (through a router) but that's not what you're doing.

Does it not work with factory default config?

 

[ryehumour]

Ah interesting. I disabled the config change and reset to the factory default config, but still no luck. I had the same issue with stock firmware (3.0.0.4.386.51665).

The issue manifested itself as not being able to see another machine via Window's network discovery, which under the hood was trying to use WDS or mDNS, both which rely on multicast packets. However, I can see the machine via IP okay.

 

[ColinTaylor]

I don't know what options you have available in repeater mode, but if you have it try changing the Wireless - Professional setting for Enable IGMP Snooping and see if that makes a difference.

 

[ryehumour]

Unfortunately, I don't see those settings available in repeater mode.

The weird part is if I initiate the mDNS service discovery query on one side of the repeater (WAN side) and then run another query on the other side (LAN side), I suddenly get info about LAN side machines sent to the WAN one. Same isn't true if I do the opposite order

 

[drinkingbird]

Unfortunately, I don't see those settings available in repeater mode.

The weird part is if I initiate the mDNS service discovery query on one side of the repeater (WAN side) and then run another query on the other side (LAN side), I suddenly get info about LAN side machines sent to the WAN one. Same isn't true if I do the opposite order

Both sides are LAN.

I'd check the devices themselves, something there may be interfering. If both are connected to the repeater or both are connected to the main router does it work correctly?

It is possible that there is a multicast bug with repeater mode, or that it just doesn't support it correctly. There are some multicast settings under advanced wireless but the defaults should be sufficient (there is probably an IGMP snooping there but I believe enabling that would actually make it worse potentially, and should not be interfering regardless). Another thought, if one client is on 5ghz and another on 2.4 there could be issues there, likely on the main router and not on the repeater. Or similar if one client is wired to the main router etc.

 

[ColinTaylor]

Which band (2.4 or 5 GHz) are you repeating and connecting to?

 

[ryehumour]

Everything is on 5GHz except for the machines wired to the repeater. My setup looks something like this

 

[ColinTaylor]

If you don't have any wireless devices connected to the RT-AC68U you could change it from a repeater to a wireless (media) bridge.

 

[ryehumour]

Swapped it to bridge mode but still getting different mDNS responses depending on which side of the router I'm on.

 

[ColinTaylor]

Do you have the Wireless - Professional page available now that you're in bridge mode?

 

[ryehumour]

Still don't

 

[drinkingbird]

Swapped it to bridge mode but still getting different mDNS responses depending on which side of the router I'm on.

How have you narrowed it down to just the repeater? The main router seems a more likely culprit. However going across the software bridge from wireless to wired on the second one I guess could be somehow interfering, it shouldn't, but anything is possible. What model is the main router?

 

[ryehumour]

The main router is an ISP provided Arris TG4482A.

I'll try capturing packets on the various devices to see if I can narrow down what's happening with the mDNS packets.

 

[drinkingbird]

The main router is an ISP provided Arris TG4482A.

I'll try capturing packets on the various devices to see if I can narrow down what's happening with the mDNS packets.

May also make sense to see what happens when both clients are connected to the arris vs when both are connected to the repeater. Two clients on the repeater should be no different than one on the repeater and one on the main wifi, at least when both clients are wireless.

When one or both are wired, in theory there could be something in the bridging interfering but pretty unlikely, its all layer 2 stuff at that point.

Maybe try mixing a wired and wireless client both on the repeater and see what happens. Although in all honesty having rarely used a repeater I have no idea if that keeps the traffic local to the repeater or still routes it through the main router. You'd think it would stay local but who knows.

To be 100% sure you could set the repeater in AP mode on a different SSID, (or same SSID but shut off your main router), and just test how two clients connected to it work (probably have to assign static IPs to them). Just for the sake of narrowing down where the problem lies.