Quick Answer

A complete no-network diagnostic walks through six layers: physical cable check, NIC driver status, IP configuration, DNS resolution, gateway reachability, and ISP-side connectivity. Run ipconfig /all, ping the gateway, ping 8.8.8.8, then ping a domain name to isolate where the failure sits in under five minutes.

Layer 1: Physical and Driver Sanity Check

Start at the cable. Reseat the Ethernet plug, swap to a known-good cable, try a different switch port. On Wi-Fi, toggle the adapter off and on and confirm the SSID list populates. In Windows Device Manager, expand Network Adapters and look for yellow exclamation marks, a missing or corrupt driver is the silent killer behind most "no internet" calls. Reinstalling the LAN driver from your motherboard manufacturer's site fixes maybe 30% of stubborn cases.

Layer 2: IP Configuration and DHCP

Open Command Prompt and run ipconfig /all. Look at the IPv4 address, if it starts with 169.254.x.x, DHCP failed and you're on an APIPA fallback. Try ipconfig /release followed by ipconfig /renew to force a new lease. If that fails, your router's DHCP server is exhausted or your NIC is blocked at the MAC level. A static IP from your router's reserved range often gets you online while you investigate further.

Layer 3: Gateway, DNS and ISP Reachability

Run ping followed by your default gateway IP. Success means LAN works; failure means cabling, switch, or router. Then ping 8.8.8.8, success here means the internet works but DNS is broken. Finally ping google.com, failure now points at DNS resolver issues. Switch DNS to 1.1.1.1 (Cloudflare) or 8.8.8.8 (Google) in your adapter properties and re-test. SA ISPs occasionally have flaky DNS; this swap fixes a surprising amount of "internet down" reports.

Frequently Asked Questions

What does an APIPA address mean for SA users?

A 169.254.x.x address means your PC couldn't reach a DHCP server. Reboot your router, check the cable to the WAN port, and ensure no third-party VPN is intercepting DHCP requests.

Should I run netsh winsock reset before deeper diagnostics?

Yes if cosmetic fixes fail. Run netsh winsock reset and netsh int ip reset in an admin Command Prompt, then reboot. This rebuilds the TCP/IP stack and resolves most software-corruption network failures.

Can loadshedding cause persistent network failures after power returns?

Yes. Routers and ONTs sometimes boot with cached state that breaks DHCP. Hard power cycle the router (30 seconds unplugged) and let the ONT re-sync to your ISP for two minutes before testing.

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