OpenLiteSpeed Jetpack connection error

Nope. I also deactivated all plugins and themes (both options, with active/deactivated LSCWP). It is about EC2 t2.micro on Ubuntu with 1-click script (all passed fine). My “XML-RPC server accepts POST requests only” is also correct. To say, I followed all Jetpack "fix tips", but no success. Last in my mind is that OLS set some firewall and maybe to add whitelisted Jetpack IP's, but to be honest, no idea what exactly I should to do (and where). Current offical Jetpack IP list is