Well what happened was, I was unable to browse the internet (Firefox and Chrome both had problems but Opera worked fine). Pinging worked. Other Windows machines didn't have problems at all. Sudo apt-get update didn't worked because it was looking up 18.104.22.168 for every mirrors I tried. I tried this with Firefox at first:
In address bar, type in about:config, filter for ipv6. There should be only 1 listed - network.dns.disableIPv6. Double click to change the value to true. Problems solved for Firefox.
I continued googling around and did this:
#in /etc/resolv.conf, changed nameserver to those of streamyx
#previously it was 192.168.1.1 which points to my router
#Generated by NetworkManager
And now everything works again. Only that if I reboot it will change back to 192.168.1.1