"Your DNS server might be unavailable."

Since yesterday, I have not been able to connect to the internet properly using my desktop computer with Windows 8.1 installed. No other devices on the same network have a problem; my other devices are all working normally.

Prior to this, my desktop's connection worked flawlessly and there have been absolutely no changes to the desktop's configuration between then and when the DNS issues started.

I have been trawling the internet since yesterday attempting to find a solution. Following is a list of things I've found and tried which have all, thus far, failed to fix the problem:

• "ipconfig /flushdns, /release, /renew" in elevated command prompt
• "netsh int ip reset" in elevated command prompt
• "netsh winsock reset" in elevated command prompt
• Disabling IPv6 - I re-enabled it shortly after finding out this did nothing
• Disabling avast! Antivirus - apparently this has caused issues with 8.1, but doesn't seem to be the culprit this time around
• Checking wireless adapter power settings - my desktop's always on High Performance so this isn't my wireless adapter being put to sleep
• Ensuring wireless adapter driver is up-to-date & that I'm using the one from the manufacturer, not a Windows-updated driver
• 'Enable IP filtering' turned off in router settings
• AES security mode selected in router settings

The only thing I found but haven't tried yet is one answer in another thread here where a user said "My ISP went in and reset the DNS settings on their end and this worked for me" - at this stage I'm not confident that that would do it either, but have contacted my ISP to see if they are able to address the issue.

Worth noting I currently have my adapter configured to use Google's Public DNS just so that I can type this message (it would have taken too long to do it on my phone). If you have any suggestions as to what could possibly fix this issue, I'm all ears. 

Thanks for your time.