I just wasted so much time trying to figure out why port forwarding
wasn't working and sure enough it was lack of NAT loopback. I was
forwarding to a hardwired Rasberry PI (running Home Assistant), and
everything looked setup correctly, but no amount...
Except, I'm getting about 450Mbps from ISP (so <500Mbps), and 150Mbps
from built-in speed test. (Even though I can get much higher by plugging
directly into network and running speedtest.net)ISP is BT in UK. Are you
sure this only effects those on >5...