Hello @ReeXNeeX,
Have you created your firewall rules to allow network traffic between the VLANs?
Based on our past experiences with the Peplink Team, you are best to enable Inter VLAN routing and then using these “Internal Network Firewall Rules” to bock the unwanted traffic between the VLANs, you can create firsly the rules for what you do want to allow and then a block rule for the rest.
You can search here in the forum for “firewall rules”, there is lots of good health discussions in the forum on how to do create these,
https://forum.peplink.com/search?expanded=true&q=firewall%20rules
Happy to Help,
Marcus 