[spectre.laser97]

This is my first post and I am not quite familiar with the networking terms so forgive me. So, I currently have a unique issue with my home network. When my ASUS AC68U router is not connected to WWAN, my AP keeps dropping the connection to all device (Phone and smart lamp).

Let me first explain my home network setup. I live in a rented room and my landlord gives access to his home wifi. However, I would like to use all of my devices in a separate subnet. Hence, I have decided to set up my router as a client. I connect to my landlord wifi via 5GHz (5GHz is in client mode) and share the internet connection to the 2.4GHz and the wired connections on a separate subnet (the Main subnet is 192.168.0.x while my room subnet is 192.168.1.x). This normally works well when my room router is connected to my landlords AP. However, my landlord has a habit of switching off his router and modem during the night (He was afraid that the router will overheat and died as it had happened before). When this happens, my phone will keep dropping and recognition to my router wifi connection. Obviously, there won't be any connection to the internet. But, it still causes other issues.

So, I mentioned that I have a smart lamp. This lamp is a DIY lamp I made using ESP8266 and uses Blynk. But instead of connecting to their public server, I have set up a local Blynk server which does not need the internet connection. I have tested this before in my university dorm room using another DD-WRT Router (Cisco EA2700) with a raspberry pi zero running the local server and the smart lamp connected on the same subnet and unplugged the WAN connection. I still maintain a stable connection to the AP even when the subnet was not connected to the internet and control my smart lamp through the Blynk app on my phone. The only difference was that I was connecting to the internet via ethernet cable, not setting the router to client mode.

I don't understand why my router frequently drops wireless connection when there is no internet connection and this already happens even before I set up the Blynk server and smart lamp at my new room. Before I could expand my local network capability, I need to solve this issue first.

So here is more detail on my local network setup.
- My ASUS AC68U used to run build r39956. Now runs build r40167. Problem still persists
- The 5GHz connection in my ASUS AC68U as client connection to my landlord AP
- My smartphone and smart lamp are connected to my room router and internet via the 2.4GHz local AP
- My Desktop and server (VM62 Mini PC, running PiHole and Blynk Server) are connected to the router via gigabit ethernet

I suspect the problem is with the router settings but don't know which one. The only way I can find to solve this is to disable the router local WiFi security entirely (open connection).