Truck will not shift down or up fro 2nd gear

Question

have had a intermittent issue for years the truck would sometimes not shift down to first gear. If I turned the key off and restarted it it would then go to first gear and drive/pull fine. Drove it Saturday 90 miles on the interstate 70-75mph no problem. Four hour later started it and now won\'t shift out of 2nd gear. Fluid is fine bought it new has had synthetic fluid changed every 50K.