Hate to reopen this,,, but
I am having the exact same issue after installing pihole last night
I had internet when I build my SD card and updated the Pi
but not, my machines can get to the internet, but the pihole cannot.
Been searching all day and not finding a resolution..
I am having the same issue output of dig google.com@8.8.8.8 for me is:
pi@pihole:~$ dig google.com @8.8.8.8
; <<>> DiG 9.10.3-P4-Raspbian <<>> google.com @8.8.8.8
;; global options: +cmd
;; connection timed out; no servers could be reached
All other computers running on the network using the pihole connect fine however
pihole -d failed to upload log to tricorder.
edit: with pihole still enabled if I stop using it as the dns server through my router I regain internet connection on the raspberry pi, but of course it's no longer serving its purpose