DNS server not responding after I have returned to the factory default

Hi. Recently, I have realized that I cannot open ports anymore. I searched around the web and saw that returning to the factory default configuration can fix the problem. I did that, but now I can't access the internet because of the "DNS server not responding" error. Luckily though, I have saved my settings before going to the factory default, and can turn back to my settings and have internet back. But I need to open some ports still, and I cannot do that with my current settings. I don't know what settings cause the problem, so it would be easier to get back to the default. So in short, Default = DNS server not responding, My own settings = Internet works, but cannot open ports.

I have looked around the web again and tried some things but they didn't work.
This is what I have tried so far :
Open command prompt window by clicking on Run –> cmd (run with administrator privilege)
netsh int ip reset c:\resetlog.txt This will reset the ip
type netsh winsock reset. This command will create a prompt to restart the computer, don’t restart now. This will help reset winsock settings. Although resetting winsock is not related to this error, this might be helpful in fixing other issues which can lead to this error.
type ipconfig /flushdns This will help in flushing the stored DNS cache.
Restart the computer and check if the issue is fixed.
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Type IPCONFIG /RELEASE
Type IPCONFIG /RENEW
Type IPCONFIG /REGISTERDNS
Type IPCONFIG /FLUSHDNS
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Make preferred DNS and all the options near it to automatic. I also tried to set it to my gateway default (which is how it was supposed to be and worked on my settings, but not default)

So, any ideas on how to fix this?

Thanks for the reply :)
It seems to affect all the devices.