I run a large wireless network completly based on mikrotik. Recently (2-3 weeks ago), certain website do not load or are very slow.
To name a few: Pretty much all ebay related sites (eg. http://www.ebay.de), also the yahoo sites (eg. http://www.yahoo.com), etrade, and numerous others.
Speed tests are excellent ping times are good, traceroutes never fail, dns always resolves.
I have been investigating this issue thinking it was either an ISP related issue or a wireless issue (altering MSS/MTU does nothing).
90% of web sites load without issue including the notorius http://www.hotmail.com
From day 1 of deploying our network I have always used DNS caching on RouterOS, however even though DNS was resolving I decided to disable it and go direct. The early tests of this seem to show my issue has been solved. Though I don’t know exactly where/when the problem began, I am assuming it must have occured when I updated to v2.9.23 some weeks ago. I am currently running v2.9.27 (problem still persist when DNS caching is on).