Hi everyone, I'm a computer engineer at a school, and after joining about a month ago, I've encountered an issue where several Windows PCs fail to connect to the internet on boot. Teachers report connectivity problems, and while unplugging and re-plugging the Ethernet cable used to help, it's become less effective. Performing 'ipconfig /release' and 'ipconfig /renew' seems to temporarily resolve the issue, but it keeps recurring. The problem primarily affects about 8-10 PCs used by the same teachers. The DHCP pool isn't full—there are around 430 addresses available within the subnet 192.168.4.0/22 and a lease time of 1 hour. Interestingly, some teachers no longer have issues, but new ones are starting to experience them. I'm feeling pretty lost on how to permanently fix this.
5 Answers
It's essential to check if there are any devices using static IPs that might overlap with your DHCP range. Things like printers or cameras could be causing conflicts.
How many DHCP servers do you have? If it’s just one, consider the configuration of your switches—are they all connected to separate core switches or just one? That could matter.
You might want to check your switch port configurations. Make sure Portfast is enabled on all user ports. This should help reduce DHCP timeouts related to the Spanning Tree Protocol.
I had a similar issue in the past that was also linked to Spanning Tree settings. It took me a while to trace it.
Consider analyzing the DHCP packets. If everything appears correct with your sending and receiving, it could help narrow down the issue.
I’ve seen DHCP logs showing 'offering lease without success,’ which isn't very helpful.
Have you tried updating the NIC drivers? Also, check the Windows event logs for any errors related to the DHCP client; they might provide clues on what’s going wrong.
There’s no network authentication in place, and I didn’t find anything useful in the logs around the time the problems occurred.
There are indeed cameras and kiosks connected that may be within the DHCP range.