I had this matter too, Vodafone came and told me my 20years old cables are rubbish, and the FritzBox have to be placed from 1.level to cellar, near to the point where the cable enter the house….Vodafone changed the connection box to my house.
Done, but now my network infrastructure was now wrong, In the last days I made a new WLAN with 4 Repeater, and new fresh cables through the house to our office rooms. Not easy in a 118years old house……
At the moment everything is fine working, even the forum.
I`am sure that the home net was the problem, because with LTE without WLAN the Forum HP works every time.
P.S. At home net NO Browser works at this time with the Forum, if I switched to LTE, Safari, Firefox, Edge and Chrome works….. Now with refurbished net, everything works too. It´s not the browser, it´s something in the static net.