Client on Flex mode can't reach WLC if using same subnet WLC9800.

[SUTARAP]

Hi,

I am encountering an issue with the AP in Flex mode. When configured to use VLAN 300, it successfully obtains an IP address and operates normally. However, it cannot ping the WLC on VLAN 300 or access the GUI. Conversely, when the client is switched to VLAN 301, everything functions as expected WLC is C9800-L-C-K9 running 17.12.3. Could anyone please advise? 

[MHM Cisco World]

Check if vlan allow in trunk of AP to SW

MHM

[marce1000]

  - Have a checkup of the  C9800-L-C-K9 configuration using the CLI command show tech wireless
     (not a simple show tech) and feed the output from that into Wireless Config Analyzer

  M.

[Flavio Miranda]

@SUTARAP 

 First, in order for a wireless client to access the WLC GUI, you need to permit. 

Configuration > Wireless: Wireless Global > Management Via Wireless: Enable

or CLI

#wireless mgmt-via-wireless

Related to the Vlan300, sounds like you have connectivity issue and it is difficult to say where the problem is as we dont know the topology. If can be firewall, it can be Access List, it can be routing and it can be vlan missing in trunk/port-channel

You need to identify where is the layer3 for vlan 300 and from there, you can try to ping the WLC using vlan 300 as source. Ping will probably fail.

You can use traceroute to see where the traffic stops. You can compare the config from vlan300 with vlan301 on your switches to identify what is different.

WLC does not have routing, so, probably the problem is not on the WLC. 

[Haydn Andrews]

From the SVI can you ping the WLC? If not then the issue is most likely a firewall/ACL between the SVI and the WLC. Or routing to the WLC

Need topology to understand better, whats different on the wired side between VLAN 300 and 301