While in the command prompt, try releasing and renewing your IP.
1. type IPCONFIG /RELEASE
2. type IPCONFIG /RENEW
3. type EXIT
If your issue still ocurrs, then it might be a router configuration problem. Try unplugging everything from your router, including the power cable. After 30 seconds, plug in your router's power cable and wait for the self-test to complete. Then plug your computer's ethernet cable into the router. Afterwards, repeat steps 1-3 above.
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I swear, troubleshooting is a science: the best discoveries are always on accident...