Some computers cant get ip from dhcp

SaberTracer · 2025-06-19T15:31:41.732Z

Having an issue where a couple laptops (win 11) are not able to get an ip address from the DHCP server. I was able to give these laptops a static address and they were able to connect to the network just fine after that. There are still plenty of unused addresses so i know that’s not the issue. Before i put them on static addresses i looked at the leased addresses that the DHCP server is handing out and the laptops are not showing up in leased address list. Its not a huge issue at the moment since giving them static addresses got them back on the network, but i was just wondering if to fully resolve the issue should i be looking at the DHCP if there is an issue there or should i be looking at the laptops.

thank you!

Jay-Updegrove · 2025-06-19T15:47:05.638Z

Check your lease pool size, does it extend all the way through the IP range or is there an unusually large block of addresses reserved?

Nerf_Herder · 2025-06-19T15:50:46.668Z

Jay Updegrove:

Check your lease pool size

This. How many devices do you have on the subnet? If you are at max, create a new subnet (vlan) and start parsing your devices

SaberTracer · 2025-06-19T15:56:48.117Z

The leasing pool size is about 150 i believe. with about 100 outside the leasing pool range. next time I’m over i can get a more accurate number

Jay-Updegrove · 2025-06-19T15:57:31.495Z

While you’re there, be ready to capture more data and answer questions as details matter. We’ll need way more info!!

SaberTracer · 2025-06-19T15:58:13.147Z

The leasing pool size is about 150 with only about 50 of the addresses being used. so there is still plenty of addresses that can be used

SaberTracer · 2025-06-19T15:58:41.340Z

will do

agenglercain · 2025-06-19T16:07:57.178Z

Are your PCs asking for DHCP from the correct source? is your DHCP listening?

To determine if a device is making DHCP requests, you can check its network configuration for DHCP settings or use command-line tools to observe DHCP traffic. Specifically, you can check if DHCP is enabled on the device and if it’s receiving an IP address. You can also use tools like Wireshark to capture and analyze network traffic related to DHCP.

Checking DHCP Status on a Device:

1. For Windows:

Open a command prompt as administrator.
Type ipconfig /all and press Enter.
Locate the network adapter you’re interested in (e.g., Ethernet or Wi-Fi).
Look for the “DHCP Enabled” line. If it says “Yes”, the device is configured to request an IP address from a DHCP server.
Look for the “IP Address” and “Subnet Mask” to see if an address has been assigned. If it’s a 169.254.x.x address, it indicates a problem with DHCP communication.

PatrickFarrell · 2025-06-19T18:13:38.154Z

Windows server handing out DHCP? There’s a problem with the the June update for servers that breaks the DHCP server and it stops handing out IP addresses.

ajason · 2025-06-19T18:19:47.273Z

this first. It’s a known issue with June’s update. You may need to uninstall the update.

@PatrickFarrell created a topic on it a few days ago:

June 2025 Server updates may cause DHCP Server to fail Windows

“The DHCP Server service might intermittently stop responding after installing this security update. This issue affects IP renewal for clients,” the company says in updates added to security advisories issued during this month’s Patch Tuesday. The list of affected Windows versions and the updates causing this issue includes: Windows Server 2016 (KB5061010) Windows Server 2019 (KB5060531) Windows Server 2022 (KB5060526) Windows Server 2025 (KB5060842) “We are working on releasing a resoluti…

spiceuser-f5kv · 2025-06-23T10:50:02.389Z

It seems that you’ve identified a potential issue with the DHCP lease on your Windows 11 laptops. Since they were able to connect with static IPs, the problem likely lies in DHCP communication. I recommend checking the DHCP settings on the server and ensuring that the laptops are configured to request DHCP from the correct server. If you’re running the June update, consider uninstalling it, as it has been reported to cause DHCP issues. Additionally, tools like Wireshark can help analyze DHCP traffic for further insights.

leeforrest3 · 2025-06-23T13:40:54.792Z

How are the device connecting to the network: Wi-Fi or Ethernet cable.

If Ethernet cable is it through a managed switch and does that port (its connected to) allow broadcasting

On your DCHP Pool size have any reserves assigned to it

Are these laptop in your AD and have the correct security groups