I have my doubts on it being a proper match, but a partial match is the 1994 film/pilot episode, Island City.
In the future, humanity develops a "fountain of youth" drug, but as many people around the world begin to take it, most begin to mutate into a barbaric proto-humanoid state. The few people immune to this side-effect of the drug band together and live in a futuristic city while the mutants live in the vast wasteland outside its gates. In an effort to save the human race and understand what went wrong, the city sends out research missions in fortified vehicles to bring back mutated humans for research, and to rescue healthy humans. The film focuses on one such squad of soldiers and scientists.
It involves a future with an altered humanity outside of the protected area. There is a military structure, with several of the leads functioning in a fighting capacity. Due to the "Fountain of Youth" drug, the characters all appear young, although some are supposed to be older. Not matching is that the transformation of humanity is due to a combination of the drug and genetics (with one of the side plots being that reproduction is decided by lights in the chest of the citizens, to avoid a genetic combination that would lead to proto-humanoid progeny), the city is surrounded by something more akin to desert land than a forest, and I don't recall cryosleep factoring into it.