In the meantime my i Phone connects to that Wi-Fi just fine.
I've tried all methods that I can find online, including renewing DHCP, deleting preference files in system folders, rebooting, deleting access passwords. I'm not connecting via router/modem so can't reset/restart them.
What you need is something else as a verification that it is not some strange interaction with your i Pad and Mac.
So if you have another Mac, i Pad or i Phone, Heck even a Windows/Linux laptop with known good wifi that you can test against the Mac. And you are connecting to it with an ethernet cable?
What is sounds like (IMHO) is that there may actually be an issue with the Wi Fi subsystem in the Mac.
Hardware or Software, dunno, it be elsewhere but we need to find where.After the system boots, you may be prompted to allow incoming connections to numerous programs and services, so accept these for now (you can always go to the Firewall settings and deny or remove entries later on) and then try connecting to the network again.While configuration changes from migrating or restoring a system can lead to this problem, at other times major system crashes or power outages can do the same.Simply follow the steps below from an administrator account and put the mentioned files in trash. You can use to solve the self-assigned IP address issue on your Mac running mac OS High Sierra, mac OS Mojave and also mac OS Catalina. On your Mac launch finder and click on Macintosh HD. One common issue that has affected OS X systems is when network interfaces are issued a self-assigned IP address, even though the system is connected to a network with a properly configured DHCP server.When this happens, other systems on the same network (often including similarly configured Macs) will be working just fine, indicating the problem lies with the Mac’s configuration and is not a compatibility issue with the networking hardware.Visit Stack Exchange I tried to connect to a public Wi-Fi on my Mac Book Pro but can't do that.When I opened the network configuration it says something like "self assigned IP".On my i Pad, I could select it, enter my password, and enjoy all the couch-based browsing I wanted.Nothing router or modem based, as far as I am aware. This morning it decided not to: here is a dummy IP address that indicates no connection can be made.) Indeed, if I reconnect my i Pad to this network, it warns that "This network is not connected to the Internet" (and "Join anyway" does, as expected, nothing). or reinstall the OS" under the last one, as it does not sound too appealing. I have some software crucial for work that has been proven incompatible with newer versions of OS X.