Does resetting network setting wipe your mvno?
No - resetting network settings just causes your baseband radio to reach out. Unless you have jail broken, this is a very safe and in fact, good thing to do as it forces a proper hand shake and registration with the cellular carriers to the extent you can do that.
Also, it lets you call your carrier and let them know that your issues are not resovled after a reset and reconnection. They can trace your communications from the date/time you reset and then get the issue to their engineering team to help you promptly (we hope).