Devices losing their IP addresses


We’ve been running into an issue lately with devices losing their IP address and becoming unavailable. It occurrs intermittently, sometimes days/weeks go by with no problems, but then we suddenly lose half the devices in a site. The only thing that seems to fix the problem is going into the DHCP client list, and unbinding a MAC address (usually we only need to unbind one). Once we do this, all the other devices come back online.

This is occurring on a 6510, with GXP2135s and GXP2170s. It’s happened over multiple firmware versions. Any ideas what could be causing this issue?


Test one of the phones on another network if possible or lab environment with a different dhcp server.
what happens if you set a static ip on a phone your ucm I am sure is on a staic ip does this device loose connection to the sip provider.

Does the screen on the phones show all zero like
what router firewall are you using rules on firewall dhcp lease expiry
sounds more like a network issue router/firewall to phones
do you have fail to ban enabled unless you can confirm the phone screens are showing its possible fail to ban may have blocked the phones


you need to check who is running the DHCP. and see from where the problem lies


It is unlikely a firmware issue as the forum would be flooded with hundreds if not thousands of complaints from users with the same issue and especially so given that the devices have no knowledge of others and (one or more) can’t by themselves prevent others from obtaining IPs.

What make/model of DHCP server? Curious now.