Issues with client roam from Remote Office flex-mode to Home Office local-mode

[anthonylofreso]

I have a hunch that people have run into this sort of thing before. (TAC case open, but curious if somebody here just knows the answer)

APs at our Home Office are in Local Mode
APs at our Remote Offices are in Flex Mode

When clients roam from a remote office to the home office, they retain their Remote Office IP address. This results in them associating to the Home Office wireless, but not having any connectivity until they perform an ipconfig /release & /renew. This is happening for multiple client types (Windows, apple ios, Android)

Client are connecting to the same WLAN with Flexconnect local switching enabled.

[pieterh]

yes encountered this before, this was believed mainly to be a client issue,

1) the client may or may not send a dhcp-discover packet

2) The client sends a dhcp-renew with the ip-address that was valid at the previous connection.

3) It should receive a dhcp-nack from the local dhcp server(s)

4) the client "ignores" the nack and keeps the old ip-adress active 
   (never checked at that time if client-firewall blocked this ???)

5) the client does not send a dhcp-discover + dhcp-request until

- the old leasetime has expired

- release/renew  issued

- or even adapter need to be disabled / enabled

situation was improved by installing new drivers at the client.

also some improvement was found in decreasing the leasetime (but introducing other issues).

and as it was attached to the "dhcp required" setting on the wlan, this was switched off.

[anthonylofreso]

Thank you for the reply

1. We do see the client make a DHCP request.
2. In the remote office, I see the DHCP server identifier as the Windows DHCP server IP
3. When the client roams to the home office, I see the DHCP server identifier as the WLC virtual IP
4. the client is requesting its' prior remote office IP after roaming to the home office

This happens for multiple client types (win 10, iphone). We're not yet making much progress with TAC.

We were wondering if using the same wlan was causing problems, as this wlan is using the same WLC interface.