A 20 Mbps internet speed is decent for basic tasks like browsing, email, and HD streaming on one device, but it starts to struggle with multiple users or heavy use like 4K streaming, large downloads, or competitive online gaming, making it “okay” for light users but “bad” for power users needing smooth multitasking. It’s good for single-user HD (1080p) streaming or gaming but less so for simultaneous 4K streams or many connected devices.