Combine username and password in one page

Description of problem:

I configured a ocserv server (OpenConnect). When I want to connect to it with Cisco Anyconnect Client for iOS or Windows, username and password will be asked in 2 separated pages, how can I combine them in one form?

Version of ocserv used:

1.1.6-3

Client used:

Any

Distributor of ocserv

Debian

Expected results:

Ask login and password in one form