Updating Asus dsl n16

I'm thinking of getting an Asus dsl n16 so I went to https://openwrt.org/toh/asus/dsl-n16u (it uses ramips mt7620)

The guide says to

"browse to http://192.168.1.1/Upgrade.asp

Upload .bin file to router"

I tried http://192.168.1.1/Upgrade.asp on my current router but got an error. What would I see if I had used an Asus dsl n16?

What .bin file is needed? I looked at the 24.10.1 downloads folder but can't understand it.
How do I upload the .bin file to the router"

I also looked at https://openwrt.org/docs/guide-quick-start/sysupgrade.luci. Which sysupgrade.bin is needed for an upgrade?

(I use Linux.)

what kind of error ?

did you reset the router 1st ?

with 32MB RAM, you don't want 24.10, even if it would exist - https://openwrt.org/supported_devices/432_warning.

did you read the statement below the grey box ?

the one called sysupgrade ?

are you sure the DSL-N16U and DSL-N16 are the same device ?

The N16 has no USB or WAN ports but the N16U does. The N16U is much harder to obtain. I can find other variants like the 12U, 14U, 55U etc. but there's no openwrt page for them.

I have a BT Homehub 5 but the info on upgrading it is too sketchy for me.