I want a list of probable causes that I can investigate, any advice appreciated.
The situation is this:
Brand new router.
SOME https sites don't work:
Examples being: Qantas, Westpac, etc.
SOME https sites do work:
The symptoms of loading are the page just sits there trying to open the page without doing anything.
Every month/2 months the issue recurs. Resetting the MTU fixes the issue temporarily.
The issue was occurring on the old router (happened 4 times) and has occurred on the new router (6 as (5 times) well.
NOTE: We have tried changing the MTU to lowest acceptable setting, issue recurs. Have tried with highest possible setting, issue recurs. Have tried dead on in the middle issue recurs, note that it still gets fixed every time (temporarily) and the time it takes to recur does not differ with the MTU value.