Choose for the task and location
A fixed desk or television may suit a cable; a phone moving between rooms needs wireless access. Good Wi-Fi can serve many tasks, and a cable does not automatically improve an already sufficient internet connection.
Check the whole wired path
Port speed, cable condition, switches and device support limit the link. A cable bypasses a particular radio path but does not remove server congestion or an internet-provider fault.
Test consistently
Compare the same device and workload when possible. Note latency and interruptions as well as transfer speed. Avoid drawing a universal conclusion from two different computers or unrelated tests.
Plan safe installation
Check cable routes, outdoor protection and suitable connectors before installation. Keep mains and network work appropriate to the setting. Where cabling is impractical, consider a measured wireless plan rather than assuming it cannot work.
Questions about this guide
When is a cable worth testing before buying network equipment?
Try a supported wired connection for a stationary device with dropouts or buffering. Compare the same task; that can help show whether the wireless link is contributing.
Can I simply route an indoor Ethernet cable across the garden?
Choose a route and materials suitable for the environment and installation. Outdoor links can involve weather, electrical and building considerations that need appropriate planning.