Connection problems to my server

Hello. when I tried to join my own server via direct contact, it downloads all the mods I have on it, and when it does it says done but it never connects to the server. if I wait it just says Connection Terminated. ran on my server about 3 days ago and then everything worked? what has happened? Tried everything possible, read about others who had similar problems, did what you wrote to them, but it doesn’t work.