I have a Thinkpad T420, with a series 3 mini dock that will not connect to 2 different external monitors that I have (one 22" Samsung and one 23" LG). The monitors both work fine as I can use them with a different PC model but when connecting the Thinkpad, they just go into power saving mode.
I've tried changing every possible display setting I can think of, but without any luck.
I've also seen the same issue with a different non-Lenovo laptop model. Which makes me wonder if there are some requirements for using certain types of external monitors that a number of laptops don't meet. However, I can't find any documented evidence to back this up.
Any help and suggestions much appreciated as I don't want to keep buying monitors in the hope that one day I get one that works...