Updates released the week of May 11, 2018 from Microsoft are keeping Windows users from connecting to servers that they can normally connect to. If you suddenly can't make a Remote Desktop (RDP) connection, go to Winsoft (\\software\winsoft; a.k.a. the "K:" drive) and double click on Fix_RDP. You should immediately be able to make your regular RDP connections; no reboot necessary.
The relevant Windows Updates are:
KB4103725 (Windows 8/10)
KB4103727 (Server 2016/2012)
KB4103718 (Windows 7)
Do NOT try to remove these updates directly. Use the patch on the K: drive instead.
If you continue to have problems connecting, contact AskIT.