configure FileZilla Server Passive Port Range:

1. Open up the FileZilla GUI on your server.
2. Click on the top menu Edit -> Settings.
3. From the tree menu click on Passive mode settings.
4. Now make sure the checkbox Use custom port range is checked and enter 50100 in the first box a and 51100 in the second.
5. Click OK

Configurating the Firewall

Lets open up the Firewall panel, press the Windows key on your keyboard and start typing firewall. The result should be Windows Firewall with advanced.... Click it or hit enter.
 

1. From the tree, select Inbound Rules.
2. In the right panel, click New Rule.
3. A windows pops up, select Port and click next.
4. Make sure TCP is selected, and enter 50100-51100 in the Specific local ports field.
5. Hit Next and make sure the Allow connection option is selected. Then hit Next again.
6. Select the zones where this rule need to be applied (in my case I have selected all the zones).
7. Click Next and give this rule a recognizable name: Passive FTP Ports - FileZilla.
8. Click on Finish, and your done.

In case you have not yet added port 21 to the Firewall you can use the same steps, but instead of using port 50100-51100 just use port 21