I’m with Zen now and my experience has been mostly great. I haven’t done any of the more technical things you’ve mentioned so I can’t comment on that, but in general they’ve been consistently reliable and fast for me. The only issue I’ve had has been due to a fault with the router a few months ago but the customer support sorted it within a day by walking me through how to factory reset the router.

Well cityfibre are the network providers and you need some one to act as an isp on the network to connect you, I went with noone internet as they provided a static ipv4 and ipv6 without cgnat, then they got bought/merged/billed not sure which by hometelecom. New customers don’t get a static ipv4, existing do. I haven’t noticed any type of blocking but that might just be my isp.

Most of the main providers do cgnat, mid contract price rises and generally questionable things. The one thing I was a bit concerned about was the pppoe connection rather than DHCP, but is doesn’t seem to have made much difference.