Reagan served in WWII but not in combat.
Starting with FDR:
FDR - never served; contracted polio in 1921, at age 39
Truman - served in the Army in WW1
Eisenhower - served in the Army in WW1 (in the US) and WW2, ETO
JFK - served in the Navy in WW2, PTO
LBJ - served in the USNR and active duty in 1940-1942
RMN - served in the Navy in WW2, PTO
Ford - served in the Navy in WW2, PTO
Carter - USNA during WW2; USN 1946-1953
Reagan - Army Reserve, 1937-1942, then called to active duty; 1942-1945,
excluded from overseas service due to poor eyesightGHWB - served in the Navy in WW2, PTO
Clinton - did not serve
GWB - served in Texas Air National Guard
Obama - did not serve
Trump - did not serve