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Have you updated your FRITZ!Box 7530 to OS 8.21 to stop ADSL crashes?
AVM has released FRITZ!OS 8.21. This maintenance update addresses stability issues found in the previous version. You should prioritize this installation to resolve specific connectivity bugs.
Rollout Timeline and Confusion
Confusion regarding release dates often arises from staggered rollouts. AVM releases firmware for different models at different times. The manufacturer began deploying FRITZ!OS 8.21 on November 17, 2025. Initial models, such as the FRITZ!Box 6660 Cable, received the firmware immediately. However, the popular FRITZ!Box 7530 received this maintenance update later, on December 8, 2025. You must verify the specific availability for your device model rather than relying on a general release date.
Critical Technical Fixes
The primary function of version 8.21 is correcting errors introduced in version 8.20. The most significant fix addresses an IPv6 interoperability bug. This specific error caused disruptions on certain ADSL connections. If you experienced intermittent signal drops or handshake failures after the 8.20 update, this patch resolves those conflicts. Sources confirm that the update stabilizes these problematic connections immediately.
Recommendation
Check your router interface today. Navigate to the system settings to manually trigger the search for updates if auto-update is disabled. Installing FRITZ!OS 8.21 ensures your network handles IPv6 traffic correctly and maintains a stable ADSL link.