I had the Never Update bullet selected, but my server still updated to A18. I didn't hit the Restart on the Right.

I want to roll the server back to 17.4, but I don't see any option to do that from the web control @ arkservers.io.

I was going to try the 17.4 Server build I have from Steam and just upload via FTP, but will that work, or will the server just get reset back to A18 on any restart?

ARK Servers provides two servers for 7Days2Die:

The most recent stable release, and the experimental release.

When TFP pushes out a stable release, in order to keep the game working for the customer base here, the game will update to the stable release.

You can try to upload via FTP, but keep in mind we'll no longer be able to provide support for the older Alpha, as The Fun Pimps have moved on from that version of the program.