Dear Mr Buysse,

Thank you very much for your enquiry.

Please check the following list for the explanation of each PPPoE error and
compare these with the ones found on your event log.

PPPoE error: DSL synchronization lost.
PPPoE error: Illegal packet from PPPoE server.
PPPoE error: Incorrect parameter.
PPPoE error: Incorrect service name.
PPPoE error: PPPoE server reports a problem.
PPPoE error: PPPoE server reports a system error.
PPPoE error: Timeout.
PPPoE error: Unknown error.

The DSL connection was cleared for the reason displayed. If the error
occurs again, contact your DSL provider.

In any case, I'd recommend to reset the FRITZ!Box by detaching the power
cord from the FRITZ!Box for roughly 10 seconds or via the user interface
via System > Reset > Restart FRITZ!Box....

Next, please have your Internet account information details and the account
itself verified by your Internet/DSL provider. Please ask your ISP for the
exact reason why your log on was rejected as they generate these error
messages.
If your ISP is not available in your FRITZ!Box, please choose "other
provider" and enter the account data as told to you by Belgacom.

Hint:
As far as I know, belgacom uses VPI/VCI 8/35.
Please get your access data from Belgacom and have the VPI/VCI values
confirmed by them.

Best regards,

Michael Ellguth (AVM Support)