Hi @Derek Tellier,
First off, not an expert. But I listen to a lot of podcasts and constantly try to learn new financial strategies.
I wouldn't stop contributing to 401k. Contribute up to the max match from the company and then save the rest.
From your post I get the impression that your question is not just about 401k but on how to get money to start investing. I'm not sure if anyone else mentioned other strategies on saving money. I listen to a podcast called Listen Money Matters. It's two smart guys talking about all things money. They have a ton of episodes and info on their website about making a budget, sticking to it, how to save for rental income properties and a lot more (one of the hosts is obsessed with buy and hold REI). They interviewed a few weeks ago the CEO of Blooom. It's a company that will help you maximize your 401k to make sure it is invested in the best options your company has to offer given your risk tolerance. I know that doesn't help with a down payment for a rental property but it may help to maximize that employer match. I think there is a link for a free analysis through the LMM website. Here is the link to the website for that particular episode. If you don't like it, it's only an hour of your time lost. It may be helpful for your situation. https://www.listenmoneymatters.com/blooom-401k/
Perhaps a combination of a reducing your living expenses, refinancing your current mortgage (if your wife and lender are ok with it) and saving as much as you can will help get you to your goal faster without losing out on your employer match money. It won't be easy, but no one said it would be. I'm still struggling with all of that as well so you aren't alone!
I don't know your work/family situation but perhaps picking up a freelance job would help save up money faster. An investor in your area may need help with something and would be willing to pay you. Reach out to people in your area. You may be surprised.
Hope this helps! Best of luck with your situation!
Laura