I can confirm that I have successfully connected Linux sstpc client with self-signed certificates following by https://docs.vyos.io/en/latest/configuration/vpn/sstp.html
vyos@RTR1# openssl req -newkey rsa:4096 -new -nodes -x509 -days 3650 -keyout /config/user-data/sstp/server.key -out /config/user-data/sstp/server.crt
Generating a RSA private key
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writing new private key to '/config/user-data/sstp/server.key'
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You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
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Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:VyOS
Organizational Unit Name (eg, section) []:
Common Name (e.g. server FQDN or YOUR name) []:198.51.100.1
Email Address []:
[edit]
vyos@RTR1# openssl req -new -x509 -key /config/user-data/sstp/server.key -out /config/user-data/sstp/ca.crt
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:VyOS
Organizational Unit Name (eg, section) []:
Common Name (e.g. server FQDN or YOUR name) []:ROOT CA
Email Address []:
sstp CLI commands
set vpn sstp authentication local-users username test password 'test'
set vpn sstp authentication mode 'local'
set vpn sstp authentication protocols 'mschap-v2'
set vpn sstp network-settings client-ip-settings subnet '100.64.2.0/24'
set vpn sstp network-settings name-server '1.1.1.1'
set vpn sstp ssl ca-cert-file '/config/user-data/sstp/ca.crt'
set vpn sstp ssl cert-file '/config/user-data/sstp/server.crt'
set vpn sstp ssl key-file '/config/user-data/sstp/server.key'
And from client-side
sstpc --cert-warn --log-level 4 --log-stderr --user=test --password=test 198.51.100.1
But before edit /etc/ppp/options and replace auth to noauth