Investing is a complex topic. Don’t just jump on it without first assessing the risk. Ask yourself what is your risk tolerance level, usually low returns equals low risk. Do you want to take a bigger risk? What is your investment window (1,5, 10 years)?
Look at your mortgage. What is your current interest rate? Do you plan to refinance it in the next 3,5,10 years?
Another alternative is to go 80/20 and pay this extra 2k per month and reduce the time you need to return your mortgage. Would that work for you?
Also, look at the cost of the investment instruments. One Financial adviser tried to sell me, unsuccessfully, a ridiculously expensive investment with lots of fees. Don’t fall for such traps and make your own research before trusting the internet for financial advice.
I hope those questions help you figure out what you really want to do.