Drop in speed

[#1]

Has anyone else experienced a significant drop in download speed this weekend?

My line was installed a week ago, connected my  Asus AX86U router directly to Openreach and setup as PPPoE (partly because the plusnet router didn't arrive for a few days after install).  I've had 500Mb solidly for the whole week across ethernet and Wi-Fi. Since the morning, download speeds have been 80-90Mb/s, I've reset router etc but no luck.

[#2]

What happens if  you put the ASUS back in?

[#3]

Possible cable fault on the cable between router and ONT  ?

80-90 Mb throughput sounds like a cable dropping to 100Mb speed

[#4]

I didn't stop using the Asus, although I did briefly swap it out with the Hub2 today and the issue continued. 

[#5]

Possibly, it is a flat cable, which can be less reliable. I've re-seated everything and now back up to 500Mb.

I have a new cable arriving anyway so can change it out if it is faulty.