By default, VTC uses port 55555 to communication with MT4 terminals. Sometimes, however, this port is already in use by other applications.
To change the default port number you need to do the following:
Open VTC and go to Setup & Configuration / Preferences tab,
Change the TPC port number to something like 55557, confirm the change by pressing ENTER,
- Restart VTC.
- Remove the MT4io EA from your MT4 chart and re-attach it making sure you change the default port number to the same one you selected in VTC