Rejecting the issuance of a visa without a reason

Hello all,

I am a 28-year Lebanese male. I applied for a visit visa and got rejected 3 times.

My employer tried to apply for an employment visa but also got rejected without knowing the reason.

In 2019, I have visited the UAE and got my visa in 5 hours. What can I do to get the visa now?

Thank you all for your help!