Fritzbox Uptime System vs Dialup

The uptime for fritzboxes displayed by checkmk seems to refer to the uptime of the internet (dialup) connection not the uptime of the system. Just now checkmk shows an uptime of 12 hours, but the fritzbox shows 117 days.

Ist that intented behavior, a bug or do i miss something?

Thanks for any hint!

Checkmk 2.4.0p37 Pro / 2.5.0p15 Community

Is someone able to confirm or deny the described behavior of the fritzbox uptime check?