Unusual 100% solid black Y axis but internet connection OK

For the past couple of days I've been getting a really strange BQM, with it only showing solid black for several hours. There were no issues at the time with my FTTC connection. I have a BT Business Smart Hub 2 in bridge mode.

See here

I've been using BQM for many years but never seen this on my graphs.

I can't see any explanation in FAQs or other posts here. Any ideas?

Edited by Toxteth_OGrady (Sat 18-Mar-23 09:20:56)

Does this explain things?

Haha, yes. Perfectly thanks. I hadn't seen that post; Talk To The Staff is one of the forum boards I don't usually read.

Cheers