Using Airplay in Network with Isolation Mode

[caoimhin]

I am in a dormitory-style house with a communal WiFi. None of my devices see one another (in the sense that AirDrop and AirPlay do not work). For example, my phone cannot send audio to my HomePod, and I cannot transfer things from my phone to my MacBook using AirDrop.

Can I connect a second router to the home network as a bridge to enable my devices to see one another?

 

[Howard2k]

Yeah you can. It's not ideal because of how wifi handles multiple simultaneous conversations (it can't) and this compounds the issue to some degree.

There are loads of ways to make it work, but something like the DLink DAP-1325 might be worth a look.
It's only 802.11n, and the bandwidth is 300Mb/s so the throughput will be far less. But depending what the rest of the air looks like (network congestion) it's probably plenty of bandwidth for music. How well it will work depends on a bunch of factors so buy it from somewhere reputable so you can return it if it's not working out.

 

[techwarrior]

Maybe, do you have an ethernet port you can plug in to?

Most WiFi routers can run in bridge mode, connecting wireless devices to the ethernet. Think of it like plugging in an Ethernet hub or switch and connecting multiple LAN devices, but in this case the LAN devices will connect wirelessly.

For some routers, you would plug the ethernet from the house router to a LAN port (not WAN). If the router has a bridge mode setting, you would plug into the WAN port on your wireless router and the bridge mode would disable DHCP and NAT for devices connecting to your Wireless signal, and pass DHCP and all traffic destined for the internet to the main house router.

So, something like:

Internet <Coax\DSL> Modem\House Router <Ethernet> Your Router in Bridge Mode <WiFi> Your WiFi Clients

Of course, your WiFi SSID and password should be different than the main house WiFi.

But, check with the owner, some may not like you to have a separate WiFi network if they have a big investment in equipment. WiFi is fickle, and adding more Access Points can cause interference that deteriorates service for everyone. For instance, many colleges have WiFi across campus and in dorms, but they have policies saying residents may not use their own WiFi equipment.

 

[caoimhin]

Yeah you can. It's not ideal because of how wifi handles multiple simultaneous conversations (it can't) and this compounds the issue to some degree.

Maybe, do you have an ethernet port you can plug in to?

Thanks for the direction. I do have physical access to the main router (hereinafter "Router 1"), which itself branches out to a hub, and then to several access points on each floor of the house. I picked up a cheap Linksys E2500 (hereinafter "Router 2") and connected its WAN/Internet port to to an open LAN port on Router 1. I kept the factory settings on Router 2 with respect to NAT and DHCP, but assigned a new SSID and password.

Out of the box, this works fine; all of my devices have internet access when connected to Router 2. AirDrop worked flawlessly (I suppose I'm not entirely clear on how AirDrop works. Evidently it's a peer to peer WiFi connection for file sharing, so the network is irrelevant. Not sure why my devices weren't appearing before, but they are now.).

More importantly, the HomePod is now appearing as an AirPlay destination. However, I take note of your cautions above. The connections haven't been completely reliable. The HomePod initially had trouble connecting to the network, although the phone and MacBook both connected to Router 2 without issue. There have been a few occasions in the last thirty minutes where there is a noticeable lag between a command on my phone and the execution on the speaker. The Home app has also indicated that the speaker has been unavailable several times.

For now, it's working with questionable reliability. Maybe it's to do with the location of the router, or perhaps its the inherent complications with this sort of set-up that you mentioned above.

I do have a question about NAT/DHCP and running the router in bridge mode. If I do this, wouldn't I lose the "LAN within a LAN" I've created? That is, wouldn't the traffic just get passed up to Router 1 to manage, thereby exposing me to the restrictions of isolation mode again?

 

[techwarrior]

In network terminology, Router 1 expects to be the only router in the house without advanced configuration.

Networking involves 7 layers of protocols, routers operate at Layer 3 (L3) and use TCP\IP Addresses (192,168.1.x) to send and receive data. But, in bridge mode, the Layer 3 routing function is disabled, and all routing occurs on L2 (Layer 2) using a MAC address such as 08:6d:41:e7:cb:20. Layer 2 can only be routed to hosts that are in the same local subnet.

The problem with not seeing your air* devices has to do with layer 2 routing\discovery. Air* devices basically send a message out to the network advertising that the service is available on a given host address, every host on the network sees the broadcast. Some routers disable this sort of broadcast as it can become quite chatty on larger networks (probably the case in your situation).

The router 2 in your setup, if acting as a bridge, will retransmit broadcasts to anything connected to it, including the WAN port to the main router. But, if the main router doesn't retransmit, it dies there... but anything connected directly (ethernet or wifi) to Router 2 will see the retransmissions.

If your Router 2 is setup in default mode, you run the risk of NAT, DHCP conflicts and might see intermittent outages, not just on your end, but the entire house. It looks like that model has a bridge mode Connection type in the internet setup, so instead of using the default DHCP Auto Config connection type, if you set it to bridge mode, that should do the trick. It will then act like a hub\switch for anything that connects directly to it, either WiFi or hardwire.

In short, a router operates at L3, but a bridge\hub\switch operates at L2. If all your devices were ethernet capable, a switch would do the trick, but if you also need WiFi, making the router a bridge L2 device accomplishes the same thing as a switch would for wired devices.