remove all mod command lines and play vainilla. then, one by one start to add mods until you find the one giving you trouble.
the master server savior patch does not need command lines, they only clog it. see if there's a mod that alters gameplay or server-sided options it will impede you from joining. make an inventory of what you have installed in your mod/custom folder, and use winrez lt to examine the mods, if they change scripts or engine files they will not be multiplayer friendly. the best way to mesh multiple mods is to extract them all into an open folder, leaving the things you like and deleting everything else, then linking it with the command box. it works just like a .rez file but without the file extension.