Does your Teamcenter instance need a certificate? If so, don't forget to add it to your Mendix project. See also: https://docs.mendix.com/refguide/app-settings/#5-certificates-tab
As my some of the other answers have stated, failed to get an HTTP response can mean a multitude of things. I get it sometimes when I have forgotten to start my test instance of Teamcenter, but some other common causes could be that your configuration might be incorrect for connecting to teamcenter.
What does that mean? I'll give you an example.
By default most Teamcenter implementations will expose active workspace over port 3000, so to login to active workspace, you go to your browser window and go to (forexample) myteamcenter.com:3000.
Like Colin mentioned above, we dont care about the active workspace link, but instead want the links to the 4-tier web client and the FMS. These will commonly appear like so:
4-Tier Web URL: myteamcenter.com:8080/tc
FMS Url: myteamcenter.com:4544
Marco gave a great answer relating to Certificates... To get that certificate, you would need to go to the active workspace link in a web browser, export the certificate, and then follow this guide to bring it into your mendix project https://docs.mendix.com/refguide/app-settings/#5-certificates-tab
Hope that helps!
Which URL have you specified and how have you ensured that it is reachable?
You may be logging into a web client (Active Workspace) URL to test, but your Mendix app needs to connect to a 4-tier server URL