Finally, IP address for the router was found to be specified by changing the IP address in default VLAN "-", and IP addresses range of LAN ports could also be specified through the VLAN "-" for LAN ports in Access mode(not Trunk mode).
None of my previous 6 routers use such indirect method to change IP addresses for router and LAN ports.
The manual (downloaded from Qnap) was useless, you have to try and error.
Hardware function and performance:
Very good - 10GbE ports(WAN/LAN) x2, 1GbE(WAN/LAN)x1, 1GbE(LAN)x3, fast OS response;
Software configuration:
Bad and disappointed on LANs setting - IP address for the router is fixed and DHCP for LANs is unable to be disabled in Wireless Router mode, requiring network professional knowledge to set VLANs for your own IP addresses for LANs and then route to WAN - very complicated, still trying.
Conclusion:
It is not for home/SMB user, better with professional networking knowledge to config IP addresses your own LANs , unless you accept to use default IP addresses range for your own LANs connected items.
4.2