Ask HN: way to work on research problem in nlp while working full time

I already have some background in nlp but I want to become an expert so I can work on harder research problems. I am mid career working full time. I don't have time for Ph.D. I saw one option to do MS Computational Linguistics from univ of Washington (https://www.compling.uw.edu/) is fully online. They have reputed faculty. But one things I saw is that their courses are very basic, and they teach diluted version of courses for professional masters program. Does anybody has any suggestion. Is there any way to work on research problem in nlp while working full time. (Please don't suggest Kaggle as it is not research).