So my internet service provider Telfort [GreenISP] transferred our connection to their own network after taking over the brand/ISP Speedlinq, but then proceeds to send an e-mail about how to configure our modem the day after. That's much fun if you don't have a functional connection because their ADSL parameters for KPN ADSL vary from the BBNed network we where connected to before. But, we got sent a cd-rom beforehand! With Windows executables to automagically configure your modem with. If it could find the modem. And you have a Windows pc. Or even the modem in the default config, which we do not, as I bridged it to my trusty Linksys wrt54g v2 so the connection would be more stable.
Thankfully I got some clues from the .ini file shipped with the executables [which could even ruin your connection in such away that only browsing is still possible] and I had us online again fairly quick. Only to discover we don't reach the 1230KB/sec down speed anymore, but only a lousy 848KB/sec, while we pay for 20MBit.
Aside from that, we chose Speedlinq with BBNed to be rid of our national telephony company KPN, but Telfort is a KPN child and transferred us happily to the KPN ADSL network. *sigh*