Problem with DHCP permanently offer/request/ack

Venta

I have the problem that from some moment on the DHCP for my MGMT Interface (VLAN 168) is no longer working correctly with DHCP, or maybe the zyxel switches like XMG2230 or XMG1915 lost control of DHCP.
What i remember is that i have set TTL to 30 days and i have tried to add a Reservation for one other device.
Not sure if this is the reason the problem began.

Have someone had the same experience?

Since approx. 8 hours i have the same entries the whole day and nebula does not show any useful information about Portstatus of those switches (it also does not show the local ip, or sometimes for a short moment).
Before it worked for approx 6 days without problem.

Screenshot of the DHCP Table for MGMT Network:

PeterUK

Really it best not to use DHCP for switches in a 192.168.168.0/24 its best to put static IP device at the high end and then limit the DHCP IP pool to not over lap.

What might of happened is a Rogue device has the IP

Zyxel_Judy

Hi @Venta ,

We checked and found there was a Nebula Cloud Service incident around the time you observed this issue, which has since been resolved as of 2026-06-15 17:53 (UTC+0). Could you please confirm whether the DHCP issue on your end has also been resolved?

If the issue persists, kindly provide the following information so we can investigate further:

• Nebula organization & site name
• MAC address of affected devices

Please also enable Zyxel Support access to your organization so our team can look into this.

Venta

https://community.zyxel.com/en/discussion/comment/85563#Comment_85563

Hallo,

i think that this could correlate. The interesting stuff is why "nebula" seems to have an impact on the Switch requesting again and again a DHCP request.
I can imagine that a device like a switch is "telling" Nebula which IP he got fails (because of nebula incident), but why is the switch in this scenario forced to once again requesting a new ip (i could also find a answer for that, but i think there should be something like a MessageQueue inside the device which is trying to send from time to time the queued messages like "i got a new ip via DHCP")?

Around the time you mentioned really the DHCP stop doing this enless loop of requesting DHCP.

Thx.
Its always good to know that it was not the local administrators fault. I spent 2 hours searching for the problem because for around one week everything was working totally normal.

Venta

https://community.zyxel.com/en/discussion/comment/85540#Comment_85540

I understand.
The situation: We have moved our office and currently are splitting our networks and so on.
So the easiest way to get it running with nebula was to use DHCP because we moved our whole serverroom with all the users and so on.
I understand that switches should have fixed IPs like also servers have!

Thx