From Winlink:

10 July 2020 ‒ The Board of Directors of the Amateur Radio Safety Foundation voted in a recent virtual meeting to deprecate the WINMOR HF mode in the Winlink system. The protocol was introduced by its author Rick Muething, KN6KB, at the 2008 ARRL/TAPR Digital Communications Conference in Chicago. It was the first popular —sound card' radio mode to offer an alternative to HF hardware modems for bulk digital transport. Rick moved on by developing the Amateur Radio Digital Open Protocol (ARDOP), which was introduced in 2015 as a replacement to WINMOR with superior speed, robustness, and multiple bandwidth options. Nevertheless, until recently, WINMOR remained popular for learning and experimentation while other more robust and better-performing new modes became the workhorses of Winlink message transport.

The Winlink Team now devotes its resources to other projects and will drop support for WINMOR on the Winlink system. Other modes offer the same advantages with superior performance.

We request all HF RMS gateway sysops still offering WINMOR to remove it in favor of ARDOP, VARA HF and Pactor 3 or 4, where permitted by local rules. In an upcoming release WINMOR will be removed from Winlink Team software, making way for better, speedier, more robust and modern HF digital modes. WINMOR had a good, long and productive run.

‒The ARSFI Board of Directors
‒The Winlink Development Team

I've just given Ardop Winlink a try and I had no problem connecting to a station in the US on 80m using my usual setup with the 7300.

For more info about ARDOP, see this Winlink page. I've also updated our Winlink How-To page and created a new Winlink ARDOP page.