Why does Infinitest keep giving me SocketExceptions and what can I do about it?

Question

I'm running Infinitest in Eclipse Neon (version numbers below). Except it won't run and in the Infinitest Console, I get this message over and over:

Error occurred during test run
java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:90)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:380)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:236)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:218)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
    at java.net.Socket.connect(Socket.java:666)
    at java.net.Socket.connect(Socket.java:606)
    at java.net.Socket.<init>(Socket.java:469)
    at java.net.Socket.<init>(Socket.java:239)
    at org.infinitest.testrunner.TestRunnerProcess.main(TestRunnerProcess.java:79)

Does anyone know what might be causing this?

Eclipse Java EE IDE for Web Developers. Version: Neon.3 Release (4.6.3) Build id: 20170314-1500

Infinitest 5.2.0

EDIT: I switched projects and got this:

Error occurred during test run
java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:90)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:380)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:236)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:218)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
    at java.net.Socket.connect(Socket.java:666)
    at java.net.Socket.connect(Socket.java:606)
    at java.net.Socket.<init>(Socket.java:469)
    at java.net.Socket.<init>(Socket.java:239)
    at org.infinitest.testrunner.TestRunnerProcess.main(TestRunnerProcess.java:79)

Similar, but not the same. I added it as perhaps it could help.