I have used -p- option with all the scans I mentioned though I have also tried just the default scan and also fast scan (-F)
I am fairly certain a -p- scan shouldve found it.
I finaly got it! The problem was that I was scanning from a wrong source port
Finally. We really need to pay attention to the reading and understanding the modules. The answer to harb lab has been laid out in the notes step by step. You just need to understand what you’re doing
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After doing the same thing 3 times I finally got it.
I had to respawn the machine until it finally worked.
ncat and patience are your friends in this challenge 
It took me 9 hours of continuous searching but as soon as I read this hint I found the answer.
" It’s true the Firewall Evasion module is the answer.
Though a small hint.
Sometimes you’ve to go down for finding the answers"
Thanks broo 
Took me a few tries but as w4rd3nX said, have patience and know where you are coming from 