Unable to resolve some webpages - ERR_CONNECTION_RESET [SOLVED]

[FatBoyNotSoSlim]

Hi Everyone,

Has anyone seen the above generic message when trying to resolve some pages through a router running Merlin's firmware? I have a brand new RT-AC87U running the latest stable version, 378.52_2, that will show the above error on some pages.
I've tried a handful of DNS servers, all resolve the correct IP addresses, using another internet connection resolves the pages fine. I've not yet tried to a VPN connection to rule out a localised issue.

Using my previous router (RT-N66U, replaced due to not able to handle 100mbit on the WAN port) was no issue for the pages, nor is running my ISPs cable modem as a router as well.

My Current set up is a RT-AC87U running the latest stable version of merlin 378.52_2
Cisco DPQ3925-X Cable modem in bridge mode.

Tested across Chrome, IE (10 and 11), Firefox on Windows 8.1, Windows 7, Server 2008, Server 2012 and Ubuntu Linux (I have plenty of VMs laying around doing various tasks...).

Suspect sites include:
www.hwbot.org
https://www.unblock-us.com/
http://architectureau.com/

I'm still doing some testing on my side to rule out MTU, and confirm 100% its the Merlin firmware as well.

If anyone else has seen the same connection error, or has ideas, I'm all ears.

Cheers

 

[RMerlin]

Since you changed routers, make sure to fully reset your cablemodem. Turn it off for about 10 minutes, then turn it back on.

It's highly unlikely to be caused by the router firmware.

 

[FatBoyNotSoSlim]

Since you changed routers, make sure to fully reset your cablemodem. Turn it off for about 10 minutes, then turn it back on.

It's highly unlikely to be caused by the router firmware.

Sure enough, that's my problem solved. After a full hour long power cycle.

Thank you very kindly.