Can't connect to an external RDS TSG server from home

We have a company RDS (Remote Desktop Server) TSG (Terminal Services Gateway) server, which allows employees to connect to an RDS session from home, so they can see a work RDS desktop from home. This works fine on their home computers using windows 7 with the following settings: However, some users have Linux at home and are trying to use freerdp 1.2.0. I've tested this on a laptop connected to the internal company LAN using the following command and it works fine: $ xfreerdp /f /rfx /cert-ignore /v:farm.company.com /d:company.com /u:administrator /p: However, if I try to use that command on a laptop, which is not using the company LAN connection, i.e. a home connection, I get this: freerdp_set_last_error 0x2000C Error: protocol security negotiation or connection failure So I'm now trying to use some of the new TSG commands in freerdp 1.2.0 as follows, but that also doesn't work. I can only see 4 TSG related commands: /g:[:port] Gateway Hostname /gu:[] or [@] Gateway username /gp: Gateway password /gd: Gateway domain I read somewhere that I only really need to use /g in my particular scenario, I may have read that incorrectly. So when I try: $ xfreerdp /f /rfx /cert-ignore /v:farm.company.com /d:company.com /g:rds.company.com /u:administrator /p: That will give me: Could not open SAM file! Could not open SAM file! Could not open SAM file! Could not open SAM file! rts_connect: error! Status Code: 401 HTTP/1.1 401 Unauthorized Content-Type: text/plain Server: Microsoft-IIS/7.5 WWW-Authenticate: Negotiate WWW-Authenticate: NTLM WWW-Authenticate: Basic realm="rds.company" X-Powered-By: ASP.NET Date: Wed, 02 Jul 2014 12:36:41 GMT Content-Length: 13 Considering the original command: $ xfreerdp /f /rfx /cert-ignore /v:farm.company.com /d:company.com /u:administrator /p: This works on a Linux laptop, which is connected to the network within the company LAN. Why can't I use a similar command (with the extra TSG parameters) on the same Linux laptop, which is connected to the internet at home? Am I not using the new TSG switches correctly?