I don't understand the argument of this being a CityFibre issue.
I literally went from a previous CityFibre provider to Vodafone and the only change from my end was the router. I've never had high pings previously but as soon as it switched to Vodafone, the ping issues started.
Like others have mentioned the first hop is a Vodafone gateway, not a CityFibre gateway. CityFibre do indeed control the fibre link from your home to their Fibre Exchange (FEX) and from the FEX to the ISP.
That said, it'd be very difficult for them to slow this down as light travels... well... at the speed of light, you'd have to coil up a fibre cable in many miles to get a significant slowdown (look at how IEX stock exchange adds latency to trades in case you're interested).
Once it hits your ISP, that's basically when the packets are actually routed through the internet but if the ISP is physically (or logically) routing your packets to a gateway that is a long distance away (or one that is very congested) then that's where the latency can occur. Now, this may not show up on a trace route because it's handled internally by the Vodafone network before it hits the internet.
I'm pretty sure the gateways (first hops) are controlled by Vodafone because the IP address belongs to an ASN number that relates to Vodafone.
Also, if this is a CityFibre issue it doesn't explain why whenever Vodafone assign a new IP, sometimes the ping issues go / come back.
This is how I understood it at least, I'm happy to be proven incorrectly; honestly it would be lovely to be disproven by a Vodafone engineer that knows what they're talking about.
I find it highly unlikely that this is a CityFibre issue and if it was, Vodafone should easily be able to see it and start asking CityFibre why (and probably more importantly how because it would require effort) they're discriminating against their ISP vs others.
