At work, we've had a persistent issue with slow response times from Google based URLs via our Comcast internet service.
Any time we try to load Google.com, YouTube.com, Drive.Google.com, ajax.googleapis.com, etc. there is a 5-20 second delay before a response is received. All other sites load fine (assuming they aren't using Google APIs), and speed tests show we're getting the right bandwidth from Comcast overall.
After a connection has been established, Google pages on that IP/domain run smoothly for a few minutes, but then the same 5-20 second delay will return.
Our network setup is pretty minimal: Comcast modem/router to a D-Link Wireless Router to a D-Link Gigabit switch. We're all running Macs and the issue happens on all of the Macs on our network. Issue happens over wireless or wired connections.
What I've tried so far:
- I've tried switching to Google's DNS server (188.8.131.52) and other DNS servers both on the router and on individual Macs, but that doesn't help.
- I spent an hour on support with Comcast; they were unhelpful and claim the issue isn't with the modem, which I never suspected was the issue. They would not escalate the issue past the basic tech support since the modem is in working order.
- I've asked about this issue on /r/Networking and several comments suggested an issue with IPv6 settings; however nothing IPv6 related is enabled on the modem or router. Individual Mac's network settings are set to "Configure IPv6: Automatically" though disabling or manually setting that doesn't matter.
- Netgear CG3000DCR modem/router provided by Comcast
- D-Link DIR-868L wireless router
- D-Link DGS-1024D Gigabit Switch
What else can I try to isolate this issue? Is it more likely that it's something on our network, or is the issue with Comcast?
Any help is greatly appreciated!