Threads lock themselves after a certain time limit to prevent people from hijacking old irrelevant threads.
The last post on that other thread is correct, it is best to separate your switch's management into its own separate VLAN so it is not on LAN. How you do that depends on your switch.
It's also best to move your default user ports to a different VLAN so that VLAN1 is only internal switch traffic.
You can access it on another VLAN by having pfSense's port tagged for both the user VLAN and management VLANs and have pfSense setup an interface on the other VLAN's subnet, and you can route between them.
The advice on the other thread was solid, but it was apparently a different issue than you were seeing, so your solution may or may not actually be relevant to that thread.