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How to connect multiple (>50) devices?

SteveH3 — Fri, 29 Dec 2023 11:56:41 GMT

I have around 50+ smart devices, many of which only work if connected to the 2.4GHz band (eg, home hub, IP cameras, speakers, thermostats, etc).

I've just bought a new tablet and it won't connect to the 2.4 or 5GHz band ("Can't obtain IP address") - presumably I have too many devices for the router (BT Hub 6) to handle.

How can I add more devices? Is there a better BT Hub? should I go for a mesh wifi network (and if so, which one)?

Any suggestions would be appreciated.

Steve

Re: How to connect multiple (>50) devices?

Keith_Beddoe — Fri, 29 Dec 2023 12:06:27 GMT

@SteveH3

Welcome to this user forum for BT Retail phone and broadband customers.

Have you tried a factory reset of the BT Home Hub?

https://www.bt.com/help/broadband/how-do-i-reset-my-bt-hub-to-its-factory-settings

Connection issues can be caused by the home hub running out of internal connections. A normal restart does not fix that as the internal routing info is stored in flash memory which is retained.

You should be able to connect more than 50 devices, possibly twice that many.

Adding extra network elements will not fix this issue, as its a bug in the home hub firmware.

Re: How to connect multiple (>50) devices?

FIZZYLP — Fri, 29 Dec 2023 12:13:20 GMT

Hello,

technically you can have unlimited devices connected to your router.

think of your speeds as a slice of cake, slower your speeds smaller the cake.

the way to visualise this (for example purposes only) is by saying your max downstream is 80mbps, 80 devices means 1mbps per device, social media uses 1mbps, YouTube requires 5mbps and streaming Netflix etc requires a minimum of 10mbps.

you can see from this example not enough bandwidth to allow all your devices to work.

if the new device won’t connect to 2.5 or 5Ghz but the rest of your devices connect well then this doesn’t sound like a router issue and more of a device issue, you may need to contact the manufacturer.

yes BT offer the Smart Hub 2 and Smart Hub Ultra these are the newest hubs the hub 6 is extremely outdated but it’s the only hub you can split the SSID on to show both 2.5 & 5Ghz so I wouldn’t recommend this if most of your devices use 2.5Ghz as you’ll need to turn of 5Ghz in your hub manager to connect all your devices then turn 5Ghz back on afterwards.

I hope this helps!

Re: How to connect multiple (>50) devices?

Keith_Beddoe — Fri, 29 Dec 2023 12:36:42 GMT

@FIZZYLP

You are limited by the number of IP addresses that the home hub can issue. Typically 192.168.1.64 to 192.168.1.252 i.e 188 devices. However the home hubs DHCP server does not release allocations that have already been used, owing to a bug, so it eventually runs out of allocations. A factory reset clears out the table and allows a fresh start.

This problem is made worse by devices which use MAC randomisation (Private Addressing), as it results in multiple allocations for a single device, of which only one is ever used.

You will see lots of "Unknown Devices" showing.

Disabling this feature on devices, and using the device MAC only, gets around this problem.

Re: How to connect multiple (>50) devices?

wkirkman — Fri, 29 Dec 2023 12:27:57 GMT

"Can't obtain IP address"

Have you checked to see what range of IP Addresses your Smart Hub is giving out via DHCP? It could be you just need to extend the range.

192.168.1.0 (for example) will give you 253 IP Addresses (excluding .0 and .255) as long as the subnet mask is set to 255.255.255.0 (/24) so you could set the range from say 192.168.1.10 - 192.168.1.250 and that would give you 240 IP Addresses to be assigned across your network.

If you used 172.16.x.x with subnet mask 255.255.0.0 you would get even more.

Subnetting is too complicated a topic to go into too much, but it could be you are only providing a range for 50 devices and so only 50 IPs can be allocated.

Worth checking.

Re: How to connect multiple (>50) devices?

c64z86 — Fri, 29 Dec 2023 13:20:45 GMT

@Keith_Beddoe

What would happen if you were to change the IP address of the device manually, in it's settings, to one that is currently not "in use"? Would the hub then have to let go of the one it has allocated and give the requested one to the device? It might be another way to work around the bug? But it is putting off the inevitable though... so sorry if it sounds silly!

Re: How to connect multiple (>50) devices?

Anonymous — Fri, 29 Dec 2023 13:28:52 GMT

If a factory reset as @Keith_Beddoe suggested isn't too painful then go for that first. I would then be inclined to split the 2.4 & 5GHz bands into separate SSIDs so that you know for certain which one you're connecting to. Some devices simply don't like trying to negotiate a connection when both bands share a single SSID.

@c64z86

As the problem is apparently with the DHCP server not releasing previously used addresses, I doubt that would help. Again as @Keith_Beddoe has said, stopping the client device from using MAC randomisation is the next best workaround to BT actually fixing the problem.

Re: How to connect multiple (>50) devices?

Keith_Beddoe — Fri, 29 Dec 2023 13:59:07 GMT

@c64z86

If you want to manually assign a static IP address to a device, then you would use an IP address outside of the DHCP range, and the connection issue would not exist.

That can be quite useful for things like CCTV cameras, provided you can actually get at the settings.

You can start at 192.168.1.2 and up to 192.168.1.63.

A bit of history

The bug did not exist on the original BT Voyager modem/routers, but appeared when the Home Hub 1 first appeared. A lot of code was inherited from the SpeedTouch range of kit, which in turn used a lot of GPL (Open Source) code.

Somehow the bit to reset the DHCP leases during a restart or power cycle, was missed out. On the early home hub 1 firmware it was possible to use a Telnet command to do this. Later firmware disabled Telnet.

As far as I am aware, a lot of the code was simply re-used in all of the later home hubs, so the initial problem still exists. A factory reset overwrites the user configuration, with the one stored as a default, which has no defined allocations.

You can overcome this by disabling the DHCP server, and using another device on your network to act as a DHCP server.

Other third party routers do not have this issue.

Re: How to connect multiple (>50) devices?

c64z86 — Fri, 29 Dec 2023 16:46:30 GMT

@Keith_Beddoe

Speaking of history... were the Voyager series the very first modems/routers that BT supplied as part of an internet package?

Sorry for going off topic here, but I'm very interested in 90s/early 2000s history of BT and the internet. I tried looking it up online but some sites say that Voyager were the first supplied routers, yet others mention Linksys and BT.

Did BT supply modems in the dial up internet era as part of the package too? Or did you have to buy your own?

Re: How to connect multiple (>50) devices?

licquorice — Fri, 29 Dec 2023 16:57:28 GMT

I've moved this post to start a new thread on a more appropriate board.

Modems were not supplied by BT in dial up days, neither did they supply ADSL modems in the very early days as far as I remember.

Re: How to connect multiple (>50) devices?

Keith_Beddoe — Fri, 29 Dec 2023 17:05:27 GMT

Yes, they were the first fully integrated unit. Prior to that there was a USB powered device which looked a bit like Stingray.

https://www.computinghistory.org.uk/det/36102/Alcatel-Stingray-ADSL-Speed-Touch-USB-Modem/

Bear in mind that BT Internet was rather late in the broadband market, but did offer dial-up access using customer`s own supplied modem. If you were lucky, you could connect at 33.6Kbs download .

I have owned most of these devices in the past, including all of the Voyager range. They even had one that gave an extra phone number over the broadband connection, so BT Digital Voice is nothing new.

Re: How to connect multiple (>50) devices?

c64z86 — Fri, 29 Dec 2023 17:28:31 GMT

Ahh ok thanks for clearing that up! Wow, those early DSL modems sure were unique and funky. 😄

What were typical DSL speeds in those early days? I read that 8mbps only really came in the later 00s, that was my first internet speed in 2009.

Was it something like 512k?

Re: How to connect multiple (>50) devices?

Keith_Beddoe — Fri, 29 Dec 2023 17:35:53 GMT

My first broadband connection was 512K, which was really fast compared to dial-up, and enabled me to cancel one of our two phone lines, as you needed two lines for dial-up, if you wanted to be able to make phone calls at the same time.

512K worked well, as the Internet was not full of adverts, so pages loaded very quickly.

Prior to the Internet, there was of course Prestel (1200 baud). Quite a bit of fun at the time.

Re: How to connect multiple (>50) devices?

c64z86 — Fri, 29 Dec 2023 17:58:42 GMT

Oh yeah there is a video on youtube of someone sending an email over Prestel in the 80s! It looked a lot like teletext 😄

I often wonder what internet speed those two would have today?

Re: How to connect multiple (>50) devices?

SteveH3 — Fri, 29 Dec 2023 18:02:31 GMT

Thanks for all the advice and information - I think this is going to become a growing issue as more IoT devices proliferate around the home.

Anyway, I will try extending my router's IP range first, then do a factory reset if that fails (I've various firewall setting I'd rather not have to re-create unless I have to!).

Steve

Re: How to connect multiple (>50) devices?

Anonymous — Fri, 29 Dec 2023 18:15:12 GMT

@SteveH3wrote:
I've various firewall setting I'd rather not have to re-create unless I have to!

You can backup your settings & restore them.

If you have devices using MAC randomisation, extending the DHCP range will be a short-term fix until those addresses are also used up. Another option to consider (maybe mentioned already) is to set static IP addresses on these devices. Typically PCs, mobiles & tablets. IoT devices are unlikely to use randomisation.

Re: How to connect multiple (>50) devices?

Keith_Beddoe — Fri, 29 Dec 2023 19:19:54 GMT

Unfortunately, any backup includes those unwanted IP allocations, so restoring them afterwards does not fix the problem.

Re: How to connect multiple (>50) devices?

licquorice — Fri, 29 Dec 2023 22:13:34 GMT

My first modem, a whole 300baud speed (300bps). Mains powered 62 type equipment practice.

Re: How to connect multiple (>50) devices?

c64z86 — Fri, 29 Dec 2023 23:28:09 GMT

Wow! That looks very confusing and complicated, I've never seen one like that before! What was it used for? Is it a specialised industrial type of modem?

Re: How to connect multiple (>50) devices?

licquorice — Sat, 30 Dec 2023 09:15:41 GMT

I used it to connect a BBC B micro to a bulletin board. It was just how the first generation of modems were constructed. It was obsolete and being scrapped by the time I rescued it in the mid eighties.

I just happened to see that one in the computing museum at Bletchley and realised it was the same as the one I had used many years ago.