Use Ethernet as a comparison, not a guarantee
A direct wired connection removes the Wi-Fi hop from that device to the router. It does not remove remote-server delays, router queues, a slow adapter, or an upstream bottleneck. Wi-Fi can be adequate for a particular task, and a wired link can still perform poorly. Investigate your actual symptom before buying equipment.
There is no universal latency table
This guide does not publish measured scores for Ethernet, Wi-Fi 5, Wi-Fi 6, or Wi-Fi 7. Results depend on hardware, placement, interference, client capabilities, traffic, route, and destination. A number taken from a different home or protocol is not a prediction for yours. Keep throughput, idle HTTP timing, timing variation, and application statistics separate.
Separate a busy connection from the wireless hop
Compare quiet and busy conditions on each interface. If delays appear when either interface is carrying traffic, inspect queueing and competing transfers as well as wireless conditions. New letter grades are withheld. The browser result uses HTTP request timing, not a direct radio or game-server probe; it cannot establish end-to-end packet loss or a separate upload-loaded latency series.
Keep the experiment controlled
Use the same device, browser, destination, and task. Connect to the same router rather than comparing a wired modem connection against a distant mesh node. Disable the unused interface, confirm which path is active, and record link speed. Alternate wired and wireless runs and repeat them; keep failures and warnings rather than selecting only the best result. Treat changes in household traffic as a separate condition.
If the difference follows Wi-Fi
Repeat the comparison closer to the access point and note the band and location. A mesh node may itself use wireless backhaul, so an Ethernet cable into that node does not necessarily remove every wireless hop. Compare application behavior as well as the test. Microsoft's connectivity troubleshooting includes checking the connection and trying Ethernet; it is a diagnostic step, not proof of one failed component.
Check the wired path before buying replacements
Inspect the cable and connector, router port, adapter or dock, and negotiated link speed. Use equipment rated for the required link and follow its specifications. A low negotiated speed warrants checking both ends, but does not identify the cable as the sole cause. No cable price guarantees sub-millisecond timing, and a wired connection does not guarantee zero retransmissions.
Read a result without overstating it
Compare the same symptom before and after one reversible change. Keep application statistics, times, conditions, and router observations alongside the browser result. If a run has missing or invalid timing evidence, do not turn its displayed speed into a valid latency claim. Read the HTTP timing limits and validity warnings and the testing policy before drawing conclusions.