[ubuntu] Net freeze while Repo Synchonizate topic

Hey guys,

i m having porblem with internet connection. When i start synchonizing repository (Github) it usually stops at 30 - 40 % and starts showing this error:

Code:

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fatal: unable to connect to github.com:
github.com: Name or service not known

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When this error shows, my computer stops receiving any data from the internet. Also i´m not able to visit any website by webbrowser (Chromium). It looks like i´m not connected to the internet. i´m connected by cable.

If i stop synchonizing after few seconds the internet starts working again.

Does anybody have an idea what is wrong with it?

Thanks in advance.