Why exactly does Legacy connector not work for you?
Native connector indeed only supports equality joins.
Legacy connector works fine, but I'm trying to find a way to have my dashboard update automatically. I have my report automatically update daily, but it only will update one sheet (not 2). If I can use a legacy connection to connect two separate excel workbooks vs 2 sheets on one workbook then it would work how I needed.
This sounds like a different problem.
Can you clarify what you mean by "it only will update one sheet"? Are you talking about Tableau sheets now or Excel sheets? Could you be more specific?