I think you’ve probably realised by now that the USB connection is only really there as a quick and dirty way of getting someone up and running with Blynk if all they have is a board with no form of internet connectivity.
It’s not a sustainable solution, as he computer being uses as the gateway needs to be on and the command window (the ‘dos’ as you call it) needs to be open all the time for the serial gateway to work.
Connection is normally very quick, provided you have the macro configured correctly.
The fact that you’ve messed-around with port-forwarding worries me. No port forwarding is necessary or appropriate unless you are running a local Blynk server that you wish to access from outside of your network, so any port forwarding changes you’ve made need to be undone.
You need to identify the COM port that your board is connected to. This is easier in Windows Device Manager, but you should be aware that plugging the board into a different USB port will probably result in a different COM port being allocated.
As far as the port is concerned, you seem to be trying to use an SSL port (8442). I’d suggest that you use port 80 or preferably 8080 instead.
Actually, the real solution is to buy a board that has built-in Wi-Fi connectivity such as a NodeMCU.
Pete.