We have a customer who has a managed IP phone system and a managed mikrotik router that we support (but not our Internet service). We are getting intermittent reports of web pages not loading completely.
I was on site a couple weeks ago, and was able to duplicate the issue, in particular outlook.com was not loading some images. I determined at that time they were unable to access the IP that google DNS was providing for the host serving those images. When I set our router to use their provider's DNS servers, they were getting a different IP which was pingable and the web page loaded completely. I could not explain why it was working on their providers DNS and not on google DNS (which we use frequently). But we left it on their providers DNS. Today they are reporting a similar issue, supposedly affecting "most websites not loading completely." They feel our router is to blame, "used to work fine before" etc. It's a mikrotik doing NAT to a single public IP, with a few port forwards for remote access to the phone system. Nothing crazy. I do have the office computers running through the port on the grandstream IP phones, but not on a separate VLAN so the phone just acts like a switch. Their provider is not responsive to the issue, other offices in the building using that provider are not having trouble. Any suggestions or thoughts?
