@Kavethis should be posted in the switching forum. I haven't used ACLs on L2 switches but they are supposed to work.
Is it simply taking 20 minutes for the changes to take effect or is packet processing slow?
What firmware are you running on the MS120?
If you enable or disable a switch port how long does that take to actually happen, 20 minutes or much quicker?
Can you add the VLAN in the rules as all the examples have the VLAN in there.
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