I reported that I could not get Tukiu Client 22.214.171.124 to connect to the website a couple weeks back (I cannot find my original post when I searched). I have just tried again with the new client (126.96.36.199) and was receiving the same issue. I finally discovered the problem is that the client/website only uses TLS 1.0 to complete the connection and I was required to disable TLS 1.0 and 1.1 for work. TLS 1.0 is now considered insecure by today's standards and the recommendation is to update to TLS 1.2 minimum (though, if you're going to the trouble, 1.3 was ratified last May, so...). To my knowledge, TLS 1.1 is still viable.
So if anyone is having similar issues, I thought I'd post my findings.
Thanks for the info TraeStorm, I will forward this to the appropriate people.
I updated .NET Framework on version 3.1.8 of the client to support .NET 4.6.1, this has native support for TLS 1.2 by default.
And I can confirm that TLS 1.2 is working for me. You guys rock!
Glad to hear it, thanks for the update