Are routers limited to number of devices?
I'm going to buy a new router, but, I've just realised that for nearly all routers I've looked at (Belkin, Netgear, D-Link) don't state the maximum number of devices which can connect concurrently.
I have a D600 and have now looked on their website, and through the manual and also find no mention of the limit (which I really need to know if there is one due to debugging another issue).
The new router will be a gift for a friend... The issue is, they have 12 devices in their house, all of which will require WiFi and another 3 devices which are to be hard wired.
Since the router websites don't mention any limitations, can I assume there is a general limit on what the number of concurrent connected devices can do or is the issue more about understanding the more devices connected, the less the performance will be due to the sharing of the resource?
My question is, without trying to determine the limit my self manually (plugging in devices until it's maxed out), is there any way to know that a certain device will work with a given number of concurrent connected devices?
There's a (theoretical) absolute limit of 65535 concurrent connections. When using SNAT or MASQUERADE, that is. As such, the maximum feasible number of devices would be somewhere near 800, to account for closing and opening connections.
A TCP connection is uniquely defined by local and remote host and port. As such, the router could establish up to 65,535 connections to the same host and port. At the same time, it could establish another 65,535 connections to another host and port.
That means you can have an overall amount of (local addresses) * (local ports = 65,535) * (remote addresses) * (remote ports = 65,535). Of course, some local ports may not be available (services hosted or port forwarding). However, it’s still more than you’ll ever need.
Naturally, this would require a network larger than /24, which poses no problem with OpenWrt and the like. Without aftermarket firmware, most routers are limited to a /24 network, leaving 253 IP addresses for hosts. Wireless connectivity might be further limited, sometimes greatly.
However, you’ll most likely run into resource exhaustion before you’ll get anywhere near these limits. Connection tracking is very hard.
I don't know if there is a limit to number of devices which can connect. It would make more sense that most routers are limited by their hardware, and will experience performance degradation as number of devices increase.
This, I suppose, largely depends on the speed of the routers CPU and available RAM, but it also would largely depend on the services running on the router, i.e. is NAT enabled, QoS, VPN, Access control, is wireless open or with password, etc. I think that the amount of traffic that devices make, is also an important factor to the limit.
I think that this also might be the reason why manufacturers do not specify number of devices which can connect, because it depends on many factors.
In theory you can have up to 255 devices connected to your router, but you will obviously see a performance hit. The performance will be determined by the internet connection you are receiving and specific hardware specification of your router.
You will need to balance load over devices in that you can have 20 devices doing very little work fine, or 2 devices with very high load bottling your connection completely. This all depends on what you want to do with your network.
Sound routers put a limit on the DHCP pool available, which you would have to look around your router settings to find (if it's there). If no such information exists then you can assume the above information. For example, on my router I have a listed range of about 100 for maximum performance, but I will never get close to this so it's largely irrelevant to me.
Looking at the [albeit] small snippet of information provided on that router from your source I can't imagine you would notice any issues with the numbers you are working with.DCHP
Source
From my professional experience: unless you are planning to connect hundreds of devices, you don't need to worry about it.
I agree with the responses of @Matthew and @D. Kasipovic, but sometimes the scientific method does not work for predictions.
I work as a computer scientist and I have deployed many (not very big: hotels and restaurants with less than 80 devices connected at the same time) WiFi networks during years (practically from the beginning of wireless 802.11 technology in networks), so I can tell you that my usual method has finally become: buy some router (or access point), install it and... good luck.
If it hangs (or there is any other strange behavior, like reboots or returning to firmware defaults automatically) often, remove it and buy a different model.
Sorry, I wanna be more theorical in my response, but I think you could lose a lot of time researching this. Simply buy any one (except those you know failed in the past).
Do you still want some good behavior model? The best I have found till now:
Buffalo WHR-HP-G54DD
Buffalo WHR-HP-GN
I hve found them to work fine 24 hours a day during months or years with 20-30 NAT clients connected to WPA WiFi transfering many network data, plus VPN server working, and they have support for DD-WRT firmware. They heat a bit, but it is not a problem if you don't put it in a small closet. Mostly the Buffalo models have proven to be stable. But remember: even them do some times hang (even with low usage and devices connected).
EDIT: Some router models have a very limited (10-20) number of available DHCP Reservation List. This could be important if you are planning to have a fixed correlation between device and IP address. This problem is, too, solved with DD-WRT firmware.