Can't connect to my own website

I have internet in the house .It is broadband that comes in from the road along a cable and I plug a router (a Fritzbox) into it giving me internet in the house

I also have a Vodafone mast in clear sight so I can use that as well.

Now my own website is unavailable on the broadband but works perfectly well on the Vodafone and I have little clear idea why this should be so.

Should I approach the internet provider of the broadband (Lightnet) in case they are blocking access for some reason?

I get my emails from my own site(both webmail and in Outlook) and perhaps that is the reason this problem has occurred