I ask for help. I have installed sstp-client.
With the command sstpc --cert-warn --save-server-route --user ****** --password ****** server, the connection is established and works well.
When I start pppd call my-file-from-/etc/ppp/peers I get an error
pppd: Error loading shared library /usr/lib/pppd/2.4.7/sstp-pppd-plugin.so: No such file or directory
pppd: Couldn't load plugin sstp-pppd-plugin.so
Where can I get this plugin?