Http response incomplete when attemting to set up ODBC connection on Ensemble.

We are trying to make an ODBC connection via our intersystems ensemble (2016.2 running on ubuntu). However, when I am testing the connection I receive a pop-up that: "Http object response incomplete or invalid.0,#R". Note that the iodbctrace.log remains empty (and it is working because on the first try it registered a 459 error that I should activate kerberos, which I did). Any advise where I should look?
I have taken the following actions:

1. Expand the cacheodbc.ini in the mgr directory as follows:

[ODBC Data Sources]
Samples = Samples
Samplesunixodbc = Samplesunixodbc
User = User
Rsmdb = Rsmdb

​[Rsmdb]
Driver          = /home/ubuntu/intersystems/fcoffice/bin/libcacheodbciw35.so
Description     = Cache ODBC driver to Rsm-db
Host            = Something.SomethingElse.com
Namespace       = FCOFFICE
UID             = SECRET
Password        =  SECRET
Port            = 1433
Protocol        = TCP
Query Timeout   = 1
Static Cursors  = 0
Trace           = on
TraceFile       = iodbctrace.log
Authentication Method   = 1
Security Level  = 2
Service Principal Name = cache/mydomain.com

Then I went to the management portal and set up the SQL Gateway connection:

• Selected odbc
• Connection Name: RsmDatabase
• Select an existing DSN: RsmDb
• Entered username again: SECRET
• Entered password again: SECRET
• Click "Test Connection"
• Received the pop-up with: "Http object response incomplete or invalid.0,#R".

I also tried some options like a different port, different credentials, different security level, different driver (8 bit instead of unicode) etc, but I keep getting the same error. Only thing is if I set Authentication Method = 0 then I recieve the following error: 

SQLState: (08S01) NativeError: [459] Message: [Cache ODBC][State : 08S01][Native Code 459]