computer with wired connection unable to browse internet/ping correctly, although Skype/torrents remain functional (intermittent issue)

Question

I'm at the end of my wits here so any help would be much appreciated. The following is an intermittent issue: it happened once before when I first moved into this flat last month, I looked into it a lot, couldn't fix it, and then it stopped happening for a few months. It is now happening again. Prior to my move I've never had this problem.

The issue is as follows. I have a desktop connected to the internet via a LAN cable through a powerline adapter. When the problem occurs, the desktop computer will be unable to browse the internet at all through web browsers. It will also be unable to sync Evernote or connect to remote computers via LogMeIn. However, my Skype will remain logged in and any torrents currently active will remain uploading/downloading at normal speeds.

Pinging standard IP addresses fails. If I disable/re-enable the connection, it will work again - but only for a few minutes before the same problem occurs. If I do a netsh int ip reset or a netsh winsock reset, nothing changes. If I do an ipconfig flushdns/release/renew, it will work again but only for a few minutes before the problem re-occurs.

I've tried to rule a couple of things out. While this is happening, my laptop/phone will function fine using wireless connections to the same router, and to the same powerline adapter that my desktop uses (the powerline adapter also creates a wireless network around it in my bedroom - this functions fine). Also, I've tried connecting my computer to a tethered connection from my mobile phone and the issue is exactly the same: it'll work for a couple minutes after a disable-reenable before failing again. So I guess the issue appears to be in my computer?

Finally, I can ping my router fine, but when I try to navigate to log into it my browser is unable to load that page. However I can log into the router fine from my laptop.

Any advice would be very much appreciated!

Edit: I've also tried upgrading my network card drivers from the old 2009 release it ran on until now to a 2013 one, and no luck.