DHCP-server assigned and deassigned. Again.

Hi all,
many of our customers still are having “DHCP-server assigned and deassigned” issue, with result their devices cannot connect to network/internet.

We use rb711/911 as CPE with dhcp server (last release RoS) and other vendor AP like wifi: tp-link, ubiquiti, netgear…
In fact the problem occurs only in wireless network.

I understood the problem appears when:

  • device must renew the dhcp lease
  • in the network exist almost a new mobile phone apple or android (samsung)


    I think there is a kind of incompatibility with these new devices when they must renew lease, and, I don’t know how, it ends up to create problems for the other devices…

The number of customers asks us support is very high, and I don’t find a solution yet.

Can someone help me?


Make sure your pool isn’t running out of addresses. Whenever you have a network with lots of transient users (they all have 3 devices with them nowadays, right?) you might need to use a larger network than /24. Try using a /22 network such as 192.168.0.1/22 (netmask for /22 is 255.255.252.0) You could also shorten your lease times to 2 hours or something like that.

Obviously dhcp pool is “in address” and the average of devices connected is very low (about 3-10).

But I found this:
https://www.net.princeton.edu/apple-ios/ipad-iphoneos32-stops-renewing-lease-keeps-using-IP-address.html


I hope that this can help someone.


PS: Apple sucks.