"host unreachable" and "failed to join session wont go away

[(PSN)HADOUKEN-__-2]

So about mid last year the "failed to join session " and "host unreachable" error messages became constant and i have absolutely no clue how to fix this. I don't lag when playing other games including warframe, I'm a good host. My connection is usually fine but for months this error has been making it almost impossible to trade or to get invited to groups especially now since the exploiter orb is here. Sometimes people invite me and it works on the first try, I invite them and it works on the first try. Other times i can't join anybody at all and its impossible for them join me for the whole day. I haven't been able to do anything because of this error, can someone please help me. (please add shoryuken emote also)