Please check your code very carefully as most of the time you may have wrongly processed your data, mixing state & next_state, or missing something important.
Besides there are many DQN variations, including a single q net, Fixed target DQN, double DQN, and dueling DQN, even RAINBOW. So, only you can fix the problem yourself as it’s really hard trying to understand how you store and processes state, next_state, action, reward, terminal in your undocumented code snippet. Their shape and data structure are not clear.