RD gateway wizards .. help?

I have a RD Gateway server to connect to a local LAN.

Only from one network I have this issue(this is only when using RD Gateway):

• Using domain\account doesn't work over DNS but user@domain works intermittently.
• When connecting using IP address I can login with domain\account without issue

On this same client machine, if I unplug from the ethernet VLAN and utilize wifi, none of the above issues exist. Same story with other client machines as well. Additionally, I created a new domain user as a test and was able to login on the problem network with domain\account. So, I deleted the problem users and recreated but still cannot utilize that user.

Any ideas how I can chase this down? Just odd to me that it is only from one network.