Using Samsung A52S5G handset I started to notice apps were loading really slowly BBC iPlayer, Amazon,Netflix all the usuals,  over Wifi YOUFIBRE 150 Mbps. The handset mobile data would load them instantly.  Youfibre live chat had no idea, iPlayer support suggested it was my ISP. Samsung live chat had no idea but tried several fixes. Anyway Youfibre engineer visited today on unrelated matter and I asked him and he had immediate resolution. The Youfibre team had enabled both bands on my NVG578LX. This he said would solve the issue, he reset router to 2ghz only , immeditely all apps are responding as fast as they should be.