Why can't I log in via WAN except with KEENETIC DDNS?

[Wise Pds]

I have a Pfsense router and connected to it a Keenetic Titan router as an access point (But in ROUTER mode, because I need the firewall). 
I want to be able to login via the Keenetic router wan ip using HTTPS (Inside the LAN) for example with IP:192.168.1.20:8001 and be able to import my autogenerated certificate in PFSENSE to be able to login without using the Keenetic DDNS.

For example creating a DNS redirection in PFSENSE from domain example.lab.com to ip 192.168.1.20.

I can do this on Asus, Netgear, Tp-link routers, how can I not do it here?

I have searched all possible ways and I can't do it. 

I want login into my keenetic titan router wan port from a lan ip (For example from a computer 192.168.1.100 to my keenetic router 192.168.1.20)
Can you implement HTTPS WAN access for any source and import certificate?
Thanks!

 

[Denis P]

21 hours ago, Wise Pds said:

wan ip using HTTPS

its not possible, you should use HTTP for ip access

[Wise Pds]

I know that.. but why i can't import my certificate generated for example with pfsense?