Hi, recently i bought a Mikrotik CRS326-24S+2Q+RM switch.

I use this switch behind a firewall with one wan and four independent lan networks.
(four public "lan" networks with a /24 subnet mask, quite a big setup...)
I didn't want to buy four separate switches for the networks behind the firewall,
so I wanted to split a bigger switch into four parts.

Each lan network (out of four) should have six ports of this 24 port switch,
which are completely isolated from the other three networks.

My question is: What is the proper way to do this setup, 1) or 2)?

1) i did four separate VLANs via bridge VLAN filtering
as described in https://help.mikrotik.com/docs/display/ROS/Bridging+and+Switching#BridgingandSwitching-BridgeVLANFiltering
and everything is working OK

2) but i found in the docs a solution via isolated switch groups
as described in https://help.mikrotik.com/docs/display/ROS/Switch+Chip+Features#SwitchChipFeatures-Isolatedswitchgroups
I didn't try this solution

which setup is the right one? (speed, standard, etc.)