Speed dropping and intermittent WiFi

[#1]

I have Unlimited Fibre Extra which seems to average 58Mbps on speed tests. Tonight it's dropped to 32Mbps, I've noticed my mobile WiFi disconnecting and reconnecting too lately. I've tried rebooting my BT Home Hub 6 router but am still getting lower speeds. Checking the forum in case others are experiencing issues?

[#2]

Speeds appeared to be back up earlier this evening, but since 8pm they have dropped once more. I tested with https://speedtest.btwholesale.com/ amongst others wired and wireless.

[#3]

A week later and the issue is still happening, it seems after 8pm my speeds drops by half or less, it looks like I'll need Plusnet to help diagnose the problem