This is one of those times when I feel pretty stupid.
We booked the MagentaMobil Business Speedbox Flex tariff from Telekom for a company event. As the Speedbox wasn’t available and the event was taking place soon, we booked a FRITZ!Box 6850 LTE at short notice.
After inserting the SIM card into the FRITZ!Box, the LTE connection was established immediately. The FRITZ!Box was also automatically assigned an IPv4 and IPv6 address. The DNS resolution worked, but every access to any website was acknowledged with an ERR_CONNECTION_TIMED_OUT. Changing the APN did not solve the problem.
I checked the FRITZ!Box logs and the only meaningful error message I saw was Unknown status for LTE_DIA_IP.
After a brief consultation with Telekom, it turned out that no data pass had yet been booked for our tariff. This must be done directly at https://pass.telekom.de; the website is also the only one directly accessible via the FRITZ!Box when connected to LTE.
And surprisingly, normal Internet access also worked after the booking.
