I connected my personal laptop to the VLAN20 port and received an IP address in the correct range.
I was able to ping the VLAN address (i.e. 192.168.1.1) and received 'Destination port unreachable' when attempting to ping devices on my home network. I presume that this message, as opposed to 'timed out', is because the packets are being rejected by the firewall?
My work device is now connected to Port 5 / VLAN20 and it has internet access and, hopefully, can't access my home network - it's an Aruba VPN device and I can't run any tests directly.
If you want to block the work VLAN from reaching the router, you can change the input rule to drop. If you go that route, you'll likely want to add traffic rules to accept DHCP and DNS from the work network.
Otherwise, the setup looks good and your results are exactly as expected.
I'm referring to the ability to access the router itself, rather than having traffic routed through it.
For example, if you were setting up a guest network in a cafe, you would not want the patrons to be able to access the admin interface or other services running on the router. Therefore, you would block all connections from the guest network that are destined for the router itself (aside from DHCP and DNS, in most cases). The router will still allow the traffic to be routed through to the internet.
Block management you want to block all IP's that may exist in your network (e.g. a double NAT) and allow only the Internet. For example block 192.168.0.0/16.