finally, the answer is here.
Microsoft Hyper-V is reserving ports, but not using them.
here we can see the reserved port ranges:
netsh int ip show excludedportrange protocol=tcp
on my system, 3306 was within an excluded range.
Microsoft has f'cked up again by making commonly used ports available for Hyper-V.
to correct his, follow the steps described here:
and reserve port 33
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