I bought this router about a week ago. It hasn't worked since, and I even took it for it to get repaired but it still doesn't work. It is connected and it says my computer is connected to the network, but when I go online it says the DNS server could not be found. I already called the company who's in charge of my internet but they say I have to call the company that sold me the router in order to get it repaired. how can I know what my DNS server is? How do I change this to make my router work?
First, which OS are you using? If you are using Windows, open a command prompt (Run/cmd), then type ipconfig /all, finally press the enter key. You'll get a list of all of your network address settings including the DNS settings the computer has been configured with. What are the DNS entries it currently has?
Some other things to consider:
What device has your Internet provider installed at your location? Is it a router? If so, this could cause some issues between their router and your router if certain settings are not set correctly.
When you set up the router did you give it DNS addresses or leave it up to your Internet provider to set them via DHCP?
When you set up the router did you set it to DHCP for your internal network? Did you set it to pass the DNS settings to the internal network?
If you did not set it to DHCP to your internal network, did you set your computer's network settings manually and place it on the correct subnet where the router is located?