Guest WLAN not working

[cJlD2ENp4PoPQ]

hi,
since several releases i have a issue with guest wlan networks.
My general WLAN uses WPA2-Enterprise with EAP-TLS authentication and AES encryption. In addition i am using a guest network with WPA2-Personal and TKIP+AES encryption. (Access Intranet enabled, MAC filter disabled).
But the clients can't connect to guest networks. I also tried WEP, but same result. Another thing is if i remove encryption, i can connect to guest network without DHCP.
The firewall blocks DHCP requests by guest networks
kernel: DROP <4>DROP IN=wl0.1 OUT= MAC=ff:ff:ff:ff:ff:ff:xx:xx:xx:xx:xx:xx:xx:xx <1>SRC=0.0.0.0 DST=255.255.255.255 <1>LEN=342 TOS=0x10 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP <1>SPT=68 DPT=67 LEN=322
kernel: DROP <4>DROP IN=wl0.1 OUT= MAC=ff:ff:ff:ff:ff:ff:xx:xx:xx:xx:xx:xx:xx:xx<1>SRC=0.0.0.0 DST=255.255.255.255 <1>LEN=342 TOS=0x10 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP <1>SPT=68 DPT=67 LEN=322


How can i solve this issue? The client supplicant tells me following:

I wpa_supplicant: wlan0: Trying to associate with SSID 'My Guest network'
I wpa_supplicant: wlan0: Associated with e0:3f:49:xx:xx:xx
I wpa_supplicant: wlan0: CTRL-EVENT-SUBNET-STATUS-UPDATE status=0
I wpa_supplicant: wlan0: Authentication with e0:3f:49:xx:xx:xx timed out.
I wpa_supplicant: wlan0: CTRL-EVENT-DISCONNECTED bssid=e0:3f:49:xx:xx:xx reason=3 locally_generated=1

My Router RT-AC66U with Firmware 380.65