question

After connecting ADB via wifi with no problem in the past, it no longer connects. I keep getting the same msg, "unable to connect". Anyone, please assist. Thanking you in advance. I have tried: in command prompt, " ADB Disconnect" and "ADB kill-server, ADB start-server". I have also gone to Task Manager and ended the ADB task. Still, no connection. I know I am following the proper course of actions to connect, because I have done it too many times in the past. I am patiently waiting to hear from all who have an solution and/or ideas. Thanks.