Today I finally worked out why some websites won’t load on my PPPoE connection. The strange thing was that some websites would load and others wouldn’t. I found that dropping the MTU setting on the router to a lower number fixed the issue.
To find the correct MTU setting for your router, contact your ISP. If your ISP is less than forthcoming with the information, you can work it out. To work out what the correct MTU should be for your ISP, ping a website that doesn’t load, then drop the MTU by multiples of 8 and try again. Keep doing this until packet loss is 0% and the website loads.