As far as I understand, you are trying to set different ranges of IP addresses for each VLAN.
An option can be put in an access rule on the firewall that stops communication between the different vlan ip ranges.
For example:
you need to go to the "firewall" tab and then to "access rules".
Make sure you know the ip ranges for both vlans
Click on Add New Rule
Action - Deny
Service - All Traffic
Log - Not Log
Source Interface - Lan
Source IP - Range and then set values to ip range of vlan 1
Destination ip - Range and then set values to ip range of vlan2
Click on Save Settings
Then repeat but reverse the source and destination ip ranges.