I was reluctant to ask a new question as there appears to be a million dns related questions on here and elsewhere already, but, I think mine might be a bit different.
An example, right now I am writing this on my Macbook Pro, connected via wifi to my Billion router and I cannot browse/ping/trace wikipedia.org. BUT, my iPhone, connected via wifi to the same router, can.
I have tried using the router provided DNS (Google) on my Macbook (ie, network settings gives my router IP for DNS server) and I have over ridden the DNS with Google DNS and OpenDNS but with zero help.
When I take my Macbook into the office, I connected via wifi to our Airport there and 50% of the time, will need to restart my Mac before it can browse.
This appears to be port 80 only! I have never had problems with other services, torrent, skype, app store (not sure what port that uses) - although, these could just be in the group of sites/services that I can access - note I am writing this on the problematic machine, so this site is fine.
Any help would be greatly appreciated. I'm desperate to fix this.
BTW - I did read this: I cannot connect to internet but my MacBook Pro detects the network and my HP computer works fine on the same network but note that I have no proxies selected.
EDIT - I just noticed while looking at other questions, that people did not have their router address as a DHCP-provided DNS server in their network prefs. So, I logged into my router and disabled 'use router as DNS server' and then added Google's primary and secondary servers to the router. My machine now shows the Google servers but the problem persists.
EDIT #2 - A client has a VPN that I connect to using Juniper Network Connect. Rebooting my machine fixes all network issues, but the second I open Network Connect, it kills it. BUT, if I sign out of Network Connect and close the VPN, the network is still broken, so whatever it changes, does not revert.