try to change both cards with another one and set tx-power to correct values (cant be more than on default)... if you have set tx-power to 16db and card have for example 40mhz channel and mcs15 only 11dbm it can demage this card.
Hello, im new on this forum but using MT for a few years... I have one test N link in production use and there is big problems with jitter but... after post from exe i try his config - with WDS ands if i compare ap-client and wds link wds working much better. 11N on MT must be on totally free channe...