BT Whole Home Wifi - looking for advice on integrating into existing setup

[Ian Manning]

My home networking is a little more complex than usual, and I am thinking of investing in BT Whole Home Wifi (a UK product) to both simplify it and improve my wifi coverage around my 3-storey house and garden. I was wondering if someone could advise on how best to implement the BT system to make the best use of my existing infrastructure.

My setup is as follows:

- Virgin Media hub running in modem mode, connected to the primary router - an Asus RT-AC68U. Both are in the study the the middle of the ground floor. The signal from the RT-AC68U doesn't extend well to either the front of the house (where I have a video doorbell) or the back garden (where I like to sit and surf/stream in the summer).

- A 24-port switch also in the study, which the Asus router is plugged into.

- Cat6 cabling from the switch in the study (via a patch panel in the study) to a number of different locations:
- the lounge at the rear of the house, where it is connected to a 12-port switch. My AV equipment in the lounge is connected to this switch
- the dining room on the first floor, at the front of the house
- the kitchen on the first floor, at the back of the house
- the bedroom on the 2nd floor, at the back of the house.

My questions are:

- Must the first BT disc be connected directly to the Asus router, or can it be connected to the 12-port switch in the lounge (which is uplinked to the 24-port switch in the study, which in turn is connected to the Asus router)? The reason being that this would maximise the number of wifi points available to me, as I could continue to use the wifi on the Asus router to provide good wifi coverage in the study, while using the BT discs to service the rest of the ground floor of the house (particularly the back garden and front of house).

- I have a couple of devices which can only be used with other devices which are on the same wifi network (e.g. the Chromecast and the video doorbell). If the Chromecast and video doorbell are connected to BT discs, but my phone is connected to the wifi on the Asus router, will these devices behave as though they are connected to the same wifi network?

 

[degrub]

Unless you have another device serving as a DHCP server besides the router, all devices will be on the same subnet ie the network will be "flat". If you have set up VLANs then obviously, some devices will be on different subnets.
Switches are transparent to the network unless you are using VLANs.

Given the assumed number of devices, you may want to run vlans to isolate some traffic, particularly if the devices do not need to talk with other devices.

 

[Ian Manning]

Yes there'll only be one DHCP server, so everything will be on the same subnet. From a wireless network perspective I wasn't sure whether the Chromecast for example would work with my phone if the Chromecast was connected to a BT disc and the phone was connected the Asus router's wifi? Same LAN but different wifi networks??

 

[degrub]

What protocol do they use to find each other - dlna ?
SSID being different should not matter, but worst case you can set the SSIDs the same. You may want that anyway for roaming.

 

[Ian Manning]

I have no idea what protocol Chromecast uses
???

 

[BiggAW]

Yes there'll only be one DHCP server, so everything will be on the same subnet. From a wireless network perspective I wasn't sure whether the Chromecast for example would work with my phone if the Chromecast was connected to a BT disc and the phone was connected the Asus router's wifi? Same LAN but different wifi networks??

As long as the BT router is the DHCP server, and all the other routers are connected not as routers, but APs only, it will be one flat network with one flat subnet, and Chromecast and whatever else will work fine. What consumer devices can't do is jump subnets or go through routers, as they are designed to be on a single subnet with a single /24 addressing space. Some apps even bomb the whole /24 with ARP just to figure out where their brand of devices are on the network. It's an ugly solution, but I guess it's fine in practice as long as you have <253 devices.

EDIT: Just to be clear, the phone and Chromecast don't have to be on the same AP or even be wireless at all (a Chromecast Ultra could be wired to Ethernet and a phone on Wi-Fi can cast to it), as long as they are on the same /24.

 

[Ian Manning]

Just to be clear, the phone and Chromecast don't have to be on the same AP or even be wireless at all (a Chromecast Ultra could be wired to Ethernet and a phone on Wi-Fi can cast to it), as long as they are on the same /24.

Hmmm...that doesn't square with what I'm currently observing. For example:
- If both Chromecast and phone are connected to the same subnet and DHCP server (i.e. my Asus router), but one is connected to 5GHz and the other to 2.4GHz wifi, then the phone cannot "see" the Chromecast
- My desktop Windows 10 machine, which is on the same subnet but is not wireless, cannot see the Chromecast

???

EDIT - sorry I've just rechecked the 2nd item and it now seems that my desktop PC (connected via ethernet) CAN now see the Chromecast.

 

[CaptainSTX]

Hmmm...that doesn't square with what I'm currently observing. For example:
- If both Chromecast and phone are connected to the same subnet and DHCP server (i.e. my Asus router), but one is connected to 5GHz and the other to 2.4GHz wifi, then the phone cannot "see" the Chromecast
- My desktop Windows 10 machine, which is on the same subnet but is not wireless, cannot see the Chromecast

???

EDIT - sorry I've just rechecked the 2nd item and it now seems that my desktop PC (connected via ethernet) CAN now see the Chromecast.

Something doesn't seem right with your setup. I have no problems casting from my PC which is wired to my Chromecast which uses WiFi. Both are on the same subnet and both use the VPN client on the router.