Unable to connect from Composer 7.3 to Content Server 7.3: "Server communication failure"

Migrateduser

Hello,
I have an urgent problem: I can't connect from Composer 7.3 to a 7.3 CS.
Everytime I try to install the Composer project to the CS, the login fails with error [DM_SESSION_E_RPC_ERROR]error: "Server communication failure".
The same Composer (exactly a copy) works correctly if used on the CS host. Obviously it's not a problem of IP address cause I put the CS IP in my hosts file and the CS is pingable from my PC.
The CS is 7.3.0130.0082 and I tried with Composer 7.3.0130.0034 and 7.3.000.0052 (the copy of that in the CS), always with the same results.
See the attached dctm_tools_....log.

Thanks in advance for any suggestion.

Arthy