Users frustrated as always on service off for nine hours...BT's ADSL network was flattened by a router outage on Tuesday evening, leaving users unable to log on for nine hours. The outage hit customers of BT Openworld ADSL and other ISPs such as Zen Internet and Freeserve, who provide ADSL using BT Wholesale's network. Internet bulletin boards were flooded with angry messages from across the country complaining at the outage. Ian Buckley, marketing manager of Zen Internet, said the problem was due to a fault with the proxy radius server, which identifies new customers as they log on to the network. He said: "We started noticing the problems with people not being able to authenticate at 5pm. They were getting the error 718 'user not known' message which they all dread." Buckley added that he received an email update from BT at 20:00(BST) on Tuesday, which was eventually repaired at 01:45 (BST) on Wednesday, almost nine hours after the first problem was spotted. Users who are already logged on do not on go through the proxy radius server so they didn't experience any interruption in their service. He said that over 50 of Zen's 800 ADSL customers had been affected. If this were reflected across the nation's 70,000 ADSL customers, then nearly 5,000 users had been hit, though no-one would have been able to log on during that time. Buckley criticised BT Wholesale for its lack of openness about the matter. "We never really get any full reason why it went down. We could do with a status page like most narrowband ISPs have, giving us up to date information about the state of the network in real-time," he told silicon.com. "They could also built better redundancy into the servers to stop it happening again," he added.