error 503 on proxy subdomains of cpanel

i get error 503 when i want to load proxy subdomains like
also i checked apache and there isn't any problem when switch to apache...

i attached screenshot of this error that captured from lsws log console.
also some errors like this happened when i got 503:

[27107] [] connection to [] on request #0, confirmed, 0, associated process: 0, running: 0, error: Connection refused!
please note:
1- curl is tested and is okay on the server to himself
2 - on apache, this problem does not exists and it's okay.
3 - i'm using lsws version 5.4.10(latest version)
4 - i tested this problem on a fresh cpanel server too and the problem was happened and alive there.


on the ports there is not any problem like 2082-2083-2086
the problem is just on proxy subdomains like or
about root access, there isn't any problem, how can i send it to you i mean a secure way?