Raspberry Pi connected to internet, can connect from windows desktop, but not from Macbook

I have got my raspberry pi 4B all set up and connected to wifi, and when I went to octopi.local the wizard loaded once, crashed, and has never connected again from the browser on my Macbook. Trying it from my brother's Windows 10 desktop on the same network connected and brought up the wizard instantly.

I have reflashed octopi onto the sd card, double checked the connection settings, logged into my router to check to see if the pi is connected, and it is. I cannot ssh into the pi or ping it, nor can I access anything through the browser with http(s)://octopi.local or the IP address given to me by the pi and the router.

I have a Netgear Nighthawk Mesh router system. Both the Pi and the Laptop are connected to the 5G band on the router. I have no idea how to fix this.

I don't have any problems connecting from a Mac. For the sake of sanity, are all the computers using the same DNS server and have addresses in the same subnet? This is usually set by the DHCP server built into the router. Is the Mac set up to use a proxy at all?

What does your DHCP server say your Pi's IP address is? If there's no entry for a host called octopi then the Pi isn't getting an IP address. Most probably because its not associating to the WiFi network - but I see from your post that it is - but there's NO IP address, possibly, or its got a self-assigned IP address in 169.254.x.x - maybe the Windows PC also got a self assigned address??? but the Mac had an IP address that was manually configured.. If in doubt, from the windows PC check with from a command prompt ifconfig/all and then run arp -a, This will broadcast an arp request on the network and you'll get a response whatever the IP addresses are - provided they are physically connected or WiFi associated you'll get a list of IP addresses and MAC addresses and names - a question mark in the first column usually accompanies a self assigned IP [but not always].

Stick the microSD card back into a laptop and check the WiFi settings, if necessary, boot the Pi with a screen and keyboard plugged in and run sudo raspi-config and check the WiFi region and country settings - it all depends where you are so that the Pi hardware selects the right channels and frequencies.

If you can, hard wire the Pi to the router with a cable, then check the DHCP server again. Log into the Pi and type ip a, this will show you the IP addresses assigned to loopback and any active physical interface. You can run arp -a from the pi also.

As a general suggestion, always change the name of the octoprint instance from the one created when you flash it - you might need more than one, and duplicated names are a recipe for dropped connections.