Many BT broadband customers are seeing extremely slow-loading web pages, and some have no access to the internet at all, after the company was hit with a double-whammy of incidents.
The lack of speed is related to a problem with third-party peering, which is the way connections between ISPs and content providers are handled, while the loss of connectivity is down to copper cable theft, BT confirmed on Wednesday.
The first issue was first spotted on Friday, when people on BT's community forums began complaining of significant packet loss and snail-like page loading speeds when connecting to a variety of sites, including those based in the UK and the US.
"Who else is getting major packet loss to various US websites including Twitter.com?" said forum member 'Al2k4'. "The 61-percent packet loss is causing the internet to slow down to a crawl."
"I have pinged from an external machine and all seems fine there, what is going on?" the user asked. "This is on BT Infinity."
According to BT, though, the slowdown is not specific to its services but arises from a peering issue with an external connectivity provider.
"We are aware that some customers are having trouble accessing some websites and online services," a BT spokesman told ZDNet. "This is due to an issue with a peering network beyond BT's service boundary. Our support team is working with a third party to resolve the issue ASAP."
BT's peering provider is Above.net, now owned by US-based Zayo. It has more than 1,000 direct and indirect peering relationships with companies and media providers around the world, including Twitter, Vodafone, Virgin Media, TalkTalk and the BBC.
However, Virgin Media and TalkTalk said they have not received any peering complaints. Above.net did not respond to a request for comment by the time of writing.
The second issue — unrelated to the peering problem — has left a number of BT's customers unable to access the internet at all as the result of a suspected copper cable theft.
BT could not say how many customers have lost service, but 13 exchanges are affected, according to the company's own status tracker.
The internet outage began at around midday on Monday and is still going on. The exchanges and dialling codes hit are:
Naturally, given the removal of copper cabling from the ground, BT's telephone customers served by these exchanges are also experiencing problems.
Cable theft continues to plague BT and cause a significant amount of downtime each year, with police involved in investigating the crimes.
"Attacks on BT's network generate tens of thousands of faults each year. BT works with local police forces, the Serious Organised Crime Agency and British Transport Police to catch cable theft criminals," the company said in a statement earlier in the year.
"The numbers of arrests related to BT cable theft are continuing to rise, with 485 arrests in 2011/12 compared to 446 in the previous year."