Does Android not allow LAN-only WiFi?

I was trying to troubleshoot the Asus router issue yesterday, and at one point had to use my phone because my laptop wasn't available.

Surprisingly, even if I disabled mobile data on my phone, the system automatically disabled the WiFi access point when it detected that it didn't have internet access.

As as result, I couldn't even go to any a LAN IPs or services, and couldn't access my router interface.

Is this a thing now, are there any workarounds?