Yeah unfortunately it seems to be an external firewall by DanEditsHD's ISP blocking it.
For anyone else: If your launcher fails to update gunz.exe and you cannot fix it, you can try to download the latest gunz.exe here:
http:// and put it in your fgunz folder.
If your browser blocks the gunz.exe download, you can download a zipped gunz.exe here:
https://puu.sh/Cz6jq/75c461402b.zip (unzip it and put it in your fgunz folder).