A.you should consider enabling, anonymous users permission group for the client -ex20 receive connector.
B.You should consider setting up a Receive connector and set the use to Client. Thereafter you should change the port for the connector.
C.You should consider setting up a Receive connector and set the use to Custom. Thereafter you should change the remote IP addresses range for the connector.
D.you should consider enabling, anonymous users permission group for the default -ex20 receive connector.