Berlin's internet is a mixed bag. Some neighborhoods already have gigabit fibre, while others are still stuck on VDSL from a street cabinet 300 meters away. The good news: rollout is picking up, and more buildings get connected every month.
the incumbent, building out FTTH but still serving many areas on VDSL2 (up to 250 Mbps).
resells Telekom and Vodafone lines, usually at a lower price.
the cable provider wired into many Berlin apartment blocks, with competitive gigabit plans.
VDSL distance dependency. If your building is far from the street cabinet, speeds drop sharply below the advertised 250 Mbps.
Vodafone cable congestion in Altbau (old building) neighborhoods with shared coaxial infrastructure.
Slow DNS resolution on default ISP resolvers. Switching to 1.1.1.1 or 9.9.9.9 noticeably improves browsing.
Frequent Telekom port exhaustion during peak hours in underserved Kiez (neighborhoods).
Before signing anything, check Telekom's and DNS:NET's fibre checkers. Knowing what's actually available at your address saves headaches.
On Vodafone cable? Make sure you have a DOCSIS 3.1 modem. Older 3.0 hardware silently caps your speed.