@RileyMax1
Same question as
@cruisetung - "home base"?
If not a duplicate IP address then another thought is that a network loop is being created. (Device A connected to Device B connected to Device C connected to Device D connected to Device A again.)
As I understand your post, your network is similar to the following line diagram where -----> represents an Ethernet connection and ~~~~> is a wireless connection:
Aussie Broadband === (fiber) ====> NBN NTD ---> Asus Router [LAN ports] ------> to your PC, your partner's PC, RPi4, and Arlo Hub
Plus ~~~~> from the router to any network wireless devices.
Home base serving the cameras - correct? How are the camera's connected?
Make and model modem?
Feel free to edit and correct my line diagram as necessary. Include other network devices as well.
Make note of the ip address and mac for each network device. There should be no duplicates. There should only be one router providing DHCP ip addresses to network devices.
Do the camera's have static IP addresses assigned?
You can use "ipconfig /all" and "arp -a" (without quotes) to help identify devices, ip addresses, and macs.
This router?
https://dlcdnets.asus.com/pub/ASUS/wireless/RT-AX58U/E23448_RT-AX58U_V2_UM_V2_WEB.pdf?model=RT-AX58U
Reference the connectivity diagrams on physically numbered Pages 12 and 13.
Also you can make use of the Administration features per Section 3.3 beginning on Page 26 to learn more about the router's and network's configuration.
Section 3.9 discusses DHCP.
Objective simply to help see the "big picture" to help with the troubleshooting effort.