Port scanning taking too long and host seeming down

Firstly I get an error that it tells me : Host seems down. If it is really up, but blocking our ping probes, try -Pn, and if I try -Pn It would take ages for example 1 hour and 49 minutes for a simple scan. Does anyone know why or have any tips? I scanned like this:

nmap -A -T4 -p- -Pn

i have the same issue , i’m blocked