Ooookay.. Took me a second to wrap my head around the layout.. Originally I only looked at the picture, which only shows a single switch.
This is an odd topography. Typically when working with switches, you want them connecting directly to the router and not connected to another switch.
You are going to have bandwidth issues out the ass, along with having a troubleshooting nightmare when something goes wrong and you need to trace packets.
Right now you have a hub and a spoke inside a hub and spoke.
Since it looks like your Asus is just an AP in this scenario, you'd be better off:
- hooking both switches to the ISP router
- enabling DHCP on the ISP router for the 2.5g switch
- set your 1g switch to a different subnet, with default gateway to your ISP router
- enable dhcp for different subnet
- add Asus for WiFi ability on new subnet
You can then play around with VLANing on the managed switch. You won't be able to separate IoT and Personal WiFi signals with VLAN. Youd need to create a guest SSID for that functionality and change the channels to 6 and 11 so you get good bandwidth
Edit: this is assuming you have a layer 3 switch, if its a layer 2 I would use the Asus as a router/AP and hook it directly to the ISP router and hook the switch up to the Asus.
Might be janky, but if you really wanted this for free you could get a speech to text program like futo, play the video and have it transcribe it and save it to a text file, then copy and paste in the subtitles