I have a working setup Wifi Calling. APs and Smartzone100 is on same management VLAN. When local switching - tunnel mode on SSID is disabled Wifi Calling (VoWIFI) is working. When I turn on Tunnel mode it is not.
All is configured with "default MTU" configuration. All L3 interfaces set to standard 1500 and also L2 interfaces on switches. I didn't played with Tunnel mode (GRE or something else on SmartZone) and MTU anywhere.
When tunnel or without tunnel, users gets same private IP addresses and same public NAT IP addresses. The only difference is that with tunnel mode theirs MAC is learned on single interface on switch and with local switching on different interface. 🙂
How to solve this? Change L2 MTU on switche interfaces to APs? And also on SmartZone?