DNS connection between building movements is not possible

[CCC3]

Both buildings use the same WLC,
You are using the same user band.

But if you move around the building, the wireless is automatically connected
Unable to connect to the internal network server.

In my opinion, communication with DNS server is not working well.

As a temporary measure, if you delete the SSID and log in again, it will be normal.

What's the problem?

[Scott Fella]

Well, on part is, does the device get an ip address and does that device also get a valid DNS server list? If yes, then it does seem like the DNS is not working as expected.  You should not be able to reach a server for an example, then roam, and not reach that server again.  You make sure that the device is not changing ip's? Also if you are using FlexConnect with local switching, you must make sure that the ap's trunk port are all configured properly of else, you will have a blackhole. You should identify the area and ap that are problems and take a closer look at everything.  Also can be an ap connected to a switch that is not forwarding the vlan to your core.

You should always provide the controller model, version, ap and any debugs.