can a 53 year old person with 17 years prior military service re-enlist in National guard or Reserve?

Stranger things have happened. I know a guy whose break in service was longer than most careers. Good luck to him

Type of separation and RE Code is relevant.

I had 9 years active and over 10 years reserve time when I redid my commission and went active duty. The age limit is pushed forward with each year of service as long as you can retire with 20 before age 62. It’s based on needs of the Army, if they are short within a specialty that will help you out.