In Huawei router forward ports 22 (ssh) and 443 (https) to the WAN IP of the Openwrt (the one that the WAN interface of Openwrt gets with dhcp or has static to communicate with the Huawei router)
In Openwrt allow in firewall the same ports from WAN.
Make sure that Luci works with https, it is not secure to connect over the internet with http.
You could also setup DDNS on Huawei or Openwrt to have a name that remains the same and will always point to the dynamic public IP the Huawei has, no matter how rarely it changes.
It is not recmmonded to open LuCI on WAN because - even if HTTPS is used, the interface can be Brute Forced, then your router is p0wned.
A VPN should be used, especially if you do not wish to use the built in SSH. BTW, you can use an SSH tunnel, you do not have to use the command line once connected securely via SSH.
I agree with @lleachii - don't expose LuCI to the web, use a VPN.
The problem is that your router appears to be a 4/32 unit, which is too small for running OpenWrt with OpenVPN installed (and there is no USB port to enable extroot).
Regarding the remote access in general - Is there a specific problem you are trying to address that you need to handle remotely?
@psherman
Thank you for suggestion. Ok, I'll reconsider it to access via remote. But is there a way to still access OpenWRT when I'm connected to the main router? My main router ip is: 192.168.100.1
while the OpenWRT is on: 192.168.1.1
Thanks in advance
SSH or VPN is the only secure way to do this. LuCI is not considered safe to expose to the Internet, whether or not https is used. Note that https is designed to protect the user from having their communications intercepted in transit, or connecting to an imposter site. It does nothing to protect the server from being hacked.
If you have the OpenWrt router connected to the main network through its WAN, (double-NATting), you have to open a port on the WAN to allow SSH in. The OpenWrt router's LAN address does not matter.
Internet (public IP) -> main router -> Open Wrt's WAN IP on the main router's LAN -> Openwrt WAN -> Dropbear SSH
On the main router:
Reserve / static lease a DHCP address for the OpenWrt router's WAN interface
Forward a port from the Internet to port 22 at the OpenWrt router's IP known above.
On OpenWrt
Open a port with source WAN, proto TCP, destination port 22
It is best not to use port 22 on the Internet, it will get probed a lot. Pick some port with a number > 10000.