LetsEncrypt cert does not work with SSTP and IPSec

Hi,
I am testing ROS 7.6rc2 CHR at my AWS instance.
Got LE cert, have it working for www-ssl.
But when I use this cert as a Server cert for SSTP - other devices can’t connect to it:
Windows says “Remote host rejected connection”
hAP ac2 says

oct/14 00:35:01 sstp,ppp,info sstp-out2: initializing... 
...
oct/14 00:35:02 sstp,ppp,info sstp-out2: terminating... - internal error (6) 
...
oct/14 00:35:02 sstp,ppp,info sstp-out2: disconnected

Exactly the same setup works fine with self-signed cert.

Whe is set LE cert as server cert for IPsec identity, I get error

Can't get private key

in CHR’s log. And again everything works fine with self-signed.


Can I use LE cert for some other purpose, not only for SSL web-fig?

Thanks all in advance.

Have you included the root CA?