I have 2 TP-Link routers running OpenWrt. My main router, an Archer c7 v5, is working great, but due to the oomkiller, I'm looking to offload minidlna to my old router, a WDR4300. This weekend, I started getting the WDR4300 set up as a NAS and secondary ethernet switch. My initial approach was to connect it to my laptop via ethernet, give it IP 192.168.2.1, and point it to 192.168.1.1 as the gateway & DNS. With DHCP, Firewall, and WAN still on, I connected the WAN port upstream. With that setup, I was able to add extroot, ksmbd & minidlna and access its file share and media server from my laptop. Devices on 192.168.1.* couldn't see the miniDLNA server, and since that was the point of the exercise, I started looking at turning the 2ndary router into a switch, following most of the Wireless Access Point tutorial (https://openwrt.org/docs/guide-user/network/wifi/dumbap). In particular, I turned off DHCP, DNS, Firewall, WAN, WAN6, and wifi. I left the IP as .2.1 as I was configuring it to be a DHCP client anyway.
So now, as the tutorial advertised, my 2ndary router acts as an ethernet switch. I have it connected upstream via a client port (WAN port doesn't work anymore; presumably because I disabled WAN) and my laptop is routed through it to the internet as I type this. However, I can't seem to log in to the router anymore. I also don't see its DLNA or file shares. I've tried ssh & http to 192.168.2.1 as well as the IPs showing as Active DHCP Leases without a hostname. No luck.
Any suggestions how I can find my 2ndary router to log in & fix my blunder? If my best option is failsafe, what should I do to fix it once I'm in failsafe mode?
Thanks for any advice!