We have frustrating issue where we are unable to isolate the problem.
We use a Cisco RV082 dual WAN router to provide load balanced Internet redundancy via an Orcon HSNS circuit and ADSL connection (Purple+). This has been working for a number of years without any issues, and continues to work without the ADSL modem connected.
Last Thursday night (a week ago) the ADSL connection began running slowly and would only connect to google related sites. Clicking on search results would result in a blank page.
Initially plugging a laptop directly into the Draytek ADSL modem (in PPPoE / PPPoA translate mode) and connecting via PPPoE on the laptop appeared to work so we ordered a replacement RV082. Over the following days we found the Laptop PPPoE connection was not consistent so suspected the Draytek modem, and replaced that as well. With both new devices we still experience issues with slow/inaccessible websites, however when we connect an ADSL modem in default modem/router mode (ie it logs in using PPPoA) the ADSL connection seems to be working normally, although we haven't left it in this mode long enough to discover if the ADSL connection is intermittent.  We have checked settings multiple times, and tried all sorts of combinations with inconsistent results for the same combination when repeated.
Does anyone have any ideas of what we might be missing, or any diagnostic methods we can try?