Before you touch a single setting, look at the back of the PC. Those two tiny lights are a diagnostic display - if you know how to read them, they tell you whether the fault is the cable, the negotiation, or something further up the chain.
Most Ethernet ports and switch ports carry two LEDs: one for link (is a connection established at all) and one for activity (is data moving right now). On many devices a single LED does both jobs, and on switches the same light often changes colour to show speed. Reading them correctly takes ten seconds and saves an hour of guessing - but read them honestly, because there is no universal colour standard.
The link LED answers one question only: did the two ends shake hands electrically? Solid means a link is established at some speed. Off means no link at all - no cable seen, a dead port, a disabled adapter, or a cable so faulty the signal never arrives. A link light that keeps switching off and on - the subject of the main fix guide - means the handshake keeps failing and restarting, which is a negotiation or signal-quality problem, not an internet problem.
The activity LED blinks once for every packet that passes. A busy network means fast, irregular flickering; an idle PC means an occasional blink as background traffic passes. Steady flickering is health, not a fault. What is not normal: an activity light that freezes solid for a long time on a home or office port, or activity blinking furiously while the PC is supposed to be doing nothing - that can hint at a traffic storm or a chatty faulty device, and is worth a second look.
On a great many switches and some PC adapters, the link light's colour carries the speed:
But treat this as a strong hint, not a standard. A few brands reverse it, some use green for every speed, and laptops with a covered or remote port may show nothing at all. When the exact meaning matters, confirm it in Windows: open the adapter status and read the negotiated Speed value in plain numbers instead of trusting the colour.
Every link has two ends, and they must agree:
See the adapter settings changed live, step by step, in the full Technical Anshu video.
Watch Full VideoAlmost certainly not. The activity light blinks for every packet, and a modern PC exchanges small amounts of traffic all the time - updates checking, cloud sync, network chatter. Constant gentle flickering is the normal look of a healthy connection.
Colours vary by brand, so do not average them - measure. In Windows, open Settings, Network and internet, Ethernet, and read the Link speed value, or check the adapter status in Control Panel. That number, not any LED, is the negotiated speed.
No electrical link exists. Work the dead-link ladder: different cable, different switch port, confirm the adapter is enabled in Device Manager, and check the switch end is lit. If every combination stays dark, the port itself may have failed and a USB or PCIe network adapter is the practical answer.