The speed you actually need
As a rule of thumb: ~5 Mbps for SD, ~10 Mbps for HD (1080p), and ~25 Mbps for 4K per stream. If two people watch at once, add the streams together. A typical 50–100 Mbps home connection comfortably runs several 4K streams.
Speed isn’t everything — stability matters more
A steady 30 Mbps beats a "100 Mbps" connection that drops every few minutes. Latency and consistency matter as much as raw speed. Run a speed test during the evening (peak hours) to see your real-world numbers.
Wired beats Wi-Fi
For your main TV, an Ethernet cable to the box/Firestick eliminates most buffering. If you must use Wi-Fi, stay on the 5GHz band and keep the device near the router. A mesh system helps in larger homes.
Why IPTV buffers even on fast internet
If your speed is fine but you still buffer, the cause is usually Wi-Fi interference, an overloaded free playlist, ISP throttling of streaming traffic (a VPN can help here), or the provider’s servers. A reputable provider with failover servers removes the last cause.