You seem to be giving some bad advice here. If the power connectors are 2.5mm why suggest that a 2.1mm connector is what is required? Maybe yours did take a 2.1mm, that is no garantee that all will. Much better to have the correct size surely?
Also that cable you are suggesting there is not rated for the sort of current in use here. Ok for LTC only mode but if you are using 2 of these with 30A each going through them that is asking for a problem. A single socket of this type cannot possibly handle 30A.