Thanks for your reply, I'll explain my setup a bit more detailed.
I have 2 routers in my network
Router A (RUTX09) is handling the WAN connectivity with 2 LTE SIM Cards, and bridging the public IP address to Router B (Asus).
Router B (Asus) is handling all the network managment like: DHCP, NAT, DNS, DynDNS, Firewall, and VPN client and VPN server. Router B (Asus) has a manual IP address and is using the net mask 255.255.255.0 and is distributing internal IP addresses over DHCP.
Physically both routers are connected as with an Ethernet Cable, LAN Port 1 on Router A (TUTX09) and WAN Port on Router B (Asus).
The reason I want to access the web interface of Router A (RUTX09) is because I need no manage the 2 WAN Ports (LTE SIM cards) e.g. switching ports, fail over scenarios.
Questions:
1) is it possible to reach the router A (RUTX09) web interface from the Router B (Asus) network? if yes, how should I configure the LAN interface on router A (RUTX09)? Fixed IP, what net mask? Or enable DHCP client to pick up an IP address from router B (Asus)?
2) Is it better to connect directly to the router A (RUTX09)? then how should look the LAN interface config on the router A (RUTX09). Manual IP address and what net mask? The client PC needs certainly a manual IP address, since no DHCP service is running on router A (RUTX09).
Thanks for helping! :-)
Cheers,
Touchwood