Users can't dowload from me and vice versa.

[Jo_501]

I changed operator and went from ADSL to Fiber Optical, and then nobody can download from me anymore. They cue up but fade away because there is no incom ing connection. I can't download either.

WinMx and MxMonitor is allowed by the firewall, but nobody gets through. Why is this happening, and is there a soloution to this mess?

I use Win 10.

[silicon_toad2000]

what have you tried so far to get it to work?
I would start with setting up the ports on your router to forward to winmx.

see if you can find your router here
http://portforward.com/english/applications/port_forwarding/WinMX/

[ale5000]

It may also depend from provider, some providers that offer optical fiber just set all their clients as private LAN so you will never ever get a pubblic IP.

Just test if your ports can be reached from outside your provider.