CRS125 with external WiFi: vlan config please help

Hello.
My current configurations:

ZTE F660 support Multi SSID.
Current IP address 192.168.1.3
I create SSID1: private_wifi and clients work fine, receive ip from DHCP Server Mikrotik.
I create SSID2 “guest_wifi” and set this SSID to VLAN 50, but I need help configure CRS125 support this VLAN 50 and connected clients:

Please, help me!
Many thanks.

Remove ether23s master port. Then bridge it in. Then add a vlan 50 to ether 23. I can post a longer response from my computer later.

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Oh… ZTE F660 cannot work with this configuration.
I take Cisco Aironet 2600 series, config two vlan (1 - native and 50), create two ssid and all work fine.

Question: I want to isolate vlan50 from other networks so that clients have access only to the Internet.
How can I do this?
Route policy or firewall rules ?
Which is preferable?