I discovered caching CDNs were throttling my everyday browsing

*Technically some ISPs can (and probably do) look at the ServerNameIndication to determine hostname and therefore whether they’re video flows or not, but I’ve not heard any real world examples of this being done.

You really don't when every modern browser sends SNI, which exposes the full domain name it's trying to connect to.

Most ISPs don't have one fat pipe to this magical "internet" place, they have multiple pipes going different places and not all of them are even listed in peeringdb, so their route to a particular CDN might be over private peering which is limited in size (e.g. 1-10Gb). Sure, then excess traffic might go over public peering but that might also then get saturated, or the ISP might force traffic over the private peering to keep the public peering clear for general traffic.

If you use a VPN then the traffic will come from a different route and different peering, thus be subject to the capacity of that route. What the OP probably wants is for Zen to have better peering with Akamai (they already have some announced routes).

Have also seen the openreach situation play out. I tried to get one of the other providers initially and they said that it would take almost a month for openreach to do the install. Contacted AA and they had it done in a couple of days. They actually show the logs of their comms with openreach in your online account so you can follow along.

Ever since the introduction of the "Automatic Compensation Scheme" the larger ISPs (zen being one of them, the scheme covers about 80% of UK customers) have had a bigger stick to whack Openreach with as Openreach have to contribute to the payments to end customers. (Some altnets such as CityFibre have also started signing up to the scheme, but iirc CityFibre don't pay per day for faults, only missed appointments and delays to connecting a new line)

One thing ISPs can do (but increases their costs) is increase the service level on your line, standard service is iirc end of 2 full business days, which most residential lines are on. Next level is end of the next working day, next level is end of same day (if reported before 1PM and next day if not) including Sundays/Bank holidays. And the next is 6Hr fix around the clock. But the higher the service level the more the ISP has to pay OR for the line. I can see "more specialised" ISPs such as A&A increasing the service level of the lines but passing that cost on the customer (one of the reasons of their increased cost, but as you said you get what you pay for, though this is just speculation as I have no idea if they actually do, just seems like something they would do - A&A are known not to be fobbed off by Openreach).

However the "Automatic Compensation Scheme" and increased service levels still doesn't stop Openreach taking their time. Recently had an FTTP outage which took a week to clear, Blinking PON, first tech who turned up determined there wasn't an issue between the pole and the premises but as he was "first level support tech" there wasn't much else he could do, he did however call someone at the exchange to poke around which a few things (which he told me was "above that persons pay-grade", so he shouldn't really be doing it but it was worth a shot as its fixed issues in the past) but no dice and the call would have to be escalated (They said it was a one-way light issue).

Next call was a missed appointment, Booked the callout, waited in until an hour after the time, called the number I got on the text and it was the same person as the callout before, OR had screwed up and put it back on his job list instead of escalating it, not the end of the world, just wish they had told me so I didn't waste most of the day waiting for someone who wasn't going to turn up.

3rd call out and this tech re-splices every splice between my house and the exchange, tech told me it was four splices (not including the splice in the "customer service point"). Still no dice. At which point they believe its a problem with a fibre card in the exchange, it will need resetting which they don't want to do in the middle of the day because it will knock everyone connected to it offline while it resets. Fair enough, he tells me they will get it done overnight, next morning still flashing PON, call the number for the 3rd tech and they confirm that the card wasn't reset and they will get it done that night.

Next day, Still Blinking PON, I'm just about to call the tech again (this is about 8am) but as I'm pulling out my phone PON goes static green, I start rebooting and reconfiguring kit (I was using my own 4G back up, I hadn't config'ed auto failback, so was killing one connection and restarting the other) when my phone rings, its the 3rd tech to tell me that they hadn't reset the card overnight again so he did it himself, something he wasn't supposed to do but heck it was getting silly at this point as it had been a week and from his end it was looking like my ONT had connected and was calling to make sure I was connected (which I was).

So even Openreach have to take the advice of the The IT Crowd every once and a while, because it turns out my week long outage was cleared by turning it off and on again.

I remember they were often referred as one of the best on ADSLguide.uk. At least in the late or early 00s.

It is sad to see the state of UK ISP not improved much after 20 years.

But a link between an ISP and a CDP provider being overloaded is quite common. The ISP is trying to get away with the minimal infrastructure investments possible, and good interconnect is expensive.

Set MTU on affected systems to 1400 or implement MSS clamping via firewall, etc.

Strategy might be different for a free-tier/cheap CDN.

The idea of paying for premium access and it negatively affecting the competition is looking at the challenge wrong. It also presumes that ISPs have one fat pipe that gets divided up, which is not usually the case unless you're a tiny ISP.

What actually affects performance and is probably the case with this user is that ISPs and CDNs need to come to an agreement over what connectivity they peer with. At scale they don't do that over public peering, it's private peering either through a third party (like Equinix or Digital Realty) or directly patching fibres within the major data centres and linking their networks together. New and unusual services will likely use public peering instead of private peering, or they won't use an tier 1 CDN like Akamai who an ISP would peer with, instead using someone like Bunny CDN, a fine CDN but not peering on the same scale.

The fairness risk comes not from the CDN or content provider 'paying' for priority, but comes from the ISP not investing in public peering. That's not the content providers fault, it's just bad operational practice. You could say it's the content providers fault for subsidising the route that gets their traffic through, but its really the ISPs poor infrastructure investments playing out. There's a small risk from content providers doing deals with ISPs to "zero rate" traffic where that ISP (or more usually cellular provider) charges users for bandwidth (or caps it), where the big content provider can use their leverage to make their service cheaper to the consumer. But the reality is that zero rating isn't particularly commercially popular, I've seen it once or twice in my career.

Farnell the company is also a turd, another example of a once great company that has gone to the dogs.

You can't even trust the stock numbers on the Farnell wesbite anymore.

Hopped on IRC and nobody was talking slowness, so I was assuming it was my end still, but then somebody mentioned sluggishness, so I spoke up.

Quick traceroute later and within 5 minutes I had a new pppoe user to try, which moved my routing to a different router in docklands, and all was good. 10 minutes later they've shifted everyone to that and taken the router out for investigation.

I wouldn't be surprised if this is related to that someway!

- Did you make sure to compare results for non-concurrent speedtest? Ie maybe those ~800 were actually 4x~200 - many speedtests open parallel connections by default.