[SOLVED] Failed to obtain IP address unifi network

[kevrick25]

Hi, I am helping someone resolve their wifi network at a small hotel they own... They have about 10 unifi AP devices throughout however they are reporting that they tried connecting new devices and they say failed to obtain IP address.

It's setup with up address 192.168.0.1 with subnet 255.255.255.0

I believe it's running out of available addresses for clients, given it's a hotel with about 16 rooms and the network can easily be overwhelmed accounting for devices from staff, smart tvs etc.

Is there a way to configure to have more available addresses for clients joining the wifi?

Any recommendation would be appreciated.

 

[Ralston18]

Make and model router or modem/router if combined?

Whoever has the necessary admin rights to the router should be able to go into the router's admin windows and check the allowed DHCP IP address range and/or the number of allowed devices.

Either one or both could be limiting device access.

The router's User Guide/Manual should have the necessary information to make the applicable changes.

 

[kevrick25]

I'm waiting on the unifi controller file from the person that set it up more than 5 years ago, so I don't know the exact setup it has...

I know unifi is handling its own DHCP on a normal subnet guessing about 256 users based on the IP I get.

Internet to them is supplied by a modem/router, that itself also has its own DHCP subnet but wifi on it is not used, it's only supplying the internet to the unifi AP devices through ethernet

Until I can get that unifi controller backup I don't know any more info, otherwise I'll have to reset and reconfigure all unifi AP devices to have control again.

 

[bill001g]

If the other person is no longer supporting the controller I would reset it just so the person that owns the device is the one who controls the passwords.
What if the system was failing and they need your help quickly. The person who needs support needs to be able to give this information to who ever is helping him quickly.

In any case it sound like the unifi controller is acting as the router for wifi network. Unless is it a very complex network it also is likely acting as the DHCP server. Note some hotels have fancy firewall systems that can authenticate guests and prevent completely open access. Many times these systems also do the DHCP function.

If you do a ipconfig /all it will show you the DHCP server address. In almost all cases of smaller networks it is the same as the gateway ip.

When you find the DHCP server you likely could expand the subnet BUT you have to then verify that any device that is not using DHCP has been changed to use the new subnet mask also. What likely will fix this without changing the subnet is to lower the lease time on DHCP addresses. The defualt is setting it to a couple days or even a week. This is fine for a network that does not have a lot of different devices but in network that is more variable it tends to be better to set this short. Something like a coffee shop could set it a hour or so and be fine and if someone was using it for more than 1 hour it will just renew. This will allow unused addresses to be placed back into the pool faster.

The unifi box tends to be rather powerful but the other downside to increasing the subnet mask to solve this is the DHCP reservations take up space in memory. For many cheap consumer routers they have limited memory and is why some do not allow you to expand the dhcp pool or support larger than a 255.255.255.0 mask.