Transitioning DHCP from old server to new

cphinx929 · 2021-09-15T21:13:07.000Z

Hey Everyone,

I feel like I’ve done this 100 times, but I’m stumped on this one.

I’m doing a pretty simple migration of DHCP from server 1 (old server) to server 2 (new server). The old is Windows Server 2012 r2 and the new is Server 2019.

Basically, I have re-created my scope and options on server 2, authorized it, and deauthorized server 1.

But when I run ipconfig /renew on my clients, the dhcp server “cannot be contacted”.

Any suggestions as to where I am going wrong? I know I’m about to be asked to provide pcaps from both ends, and I will. I’m just curious if I’m missing an obvious step or something like that.

Thanks in advance!

da-schmoo · 2021-09-15T21:37:16.000Z

What if you /release before doing the /renew? What happens if you reboot?

cphinx929 · 2021-09-15T21:47:05.000Z

Well, you’re the magic man tonight. I just initiated a reboot of a test group and after that, those clients starting pulling IP addresses. Looks like I just need to wait on a lease renewal and we’re good to go.

In fact, I think that’s where I went wrong.

johnrobertson5580 · 2021-09-15T22:27:24.000Z

I got that “cannot be contacted” when I migrated our DHCP server, only on the test group. The clients that the lease ran out and renewed on their own we’re fine.

Whatever. It’s been working fine ever since.

Internet_Schneider · 2021-09-20T06:07:36.000Z

Have you seen this? Unable To Contact Your DHCP Server [Solved] .

cphinx929 · 2021-09-20T09:42:42.000Z

I did a few of those steps during our initial trouble shooting. Including disabling and re-enabling DHCP on the clients. I even tried two different DHCP servers (first was the server where I wanted DHCP and when that wasn’t working, I tried our router - same issue on both).

Shortly thereafter, I rebooted the server where I wanted DHCP and everything seemed to come around after that. I don’t recall requiring a reboot on the server for DHCP to kick in but it seemed to fix it.