Clients Can't Connect to /23 VLAN

[GJ1]

Hi all. We're getting DHCP errors for some clients starting today. The VLAN is a /23 but I've counted up 254 leased addresses so plenty spare.

Prior to today we haven't had any issues; we've had about 40 people move into the office but that doesn't explain why a client can't connect in terms of address space (there were 5/5 DHCP errors on the dashboard).

The DHCP server is on our firewall and no configuration changes have been made. The total of 254 makes me suspicious- perhaps the Meraki doesn't see the VLAN as a /23? We're using a mix of MR32s and MR42s and are using bridged mode.

Any pointers would be appreciated!

[jdsilva]

Hey @GJ1 ,

Are you able to confirm that your DHCP server is receiving the DHCP discovers or requests? Perhaps in the logs on that device or via a packet capture?

A packet capture should also tell you if replies are being sent by your server, and received by your client. If they are not being sent then I'd look further into the DHCP server. 

If the requests aren't making it to the DHCP server then check the L2 path between the client and the server, or if there's a DHCP helper then check that too.

[NolanHerring]

Is it an MX that is acting as the DHCP server?
Can you double check the subnet settings and DHCP scope settings

[ThibaultH]

Hi GJ1 👨‍💻

Do you have a start of a network schema to provide us to ease the troubleshooting ?

What kind of client is it ? Wired, Wireless ? Any specs to provide us ?

What kind of DHCP are you using ? Do you actually see the request coming in the log of your DHCP Server ?

Do you also have a live views of the DHCP leases actually taken ?

Can't it be something linked with leases duration ?

🤘

[PhilipDAth]

Perhaps there are some large DHCP reservations eating up the /23?

[GJ1]

Hi all. Issue resolved - even though the VLAN is a /23 the scope was only set to assign 254 IPs. Increased the scope now so all good. Thanks a lot for the help.

[NolanHerring]

Thanks for the update @GJ1 

I had a feeling it was that 😃

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