Why is my computer failing to download all kinds of files on all browsers?
Most issues as you have can be solved by a TCP/IP Reset / DNS Flush. I have done this for a number of similar issues over the years.
Open cmd.exe with Run as Administrator
netsh int ip reset c:\resetlog.txtipconfig /flushdns- restart the computer and test.
You may also wish to / need to update the Fritz Stick Driver so as to avoid future problems.