Apple iPhone 13 Pro Max will not connect to Wi-Fi or keeps disconnecting

The checks in more detail

The 13 Pro Max has a Private Wi-Fi Address option and a Limit IP Address Tracking setting that some routers and corporate networks reject, so turn off the private address for that network under the network's info button. Check Local Network permission for apps if a smart-home app cannot see devices. If the router's security uses an old mode, the phone warns about weak security. Reset Network Settings clears all of it but also removes saved passwords. iOS updates fix connectivity bugs, so install the latest.

The phone also shows an unlocked Wi-Fi networks list with a Privacy Warning for networks that block the private address, and a tap on the warning explains it. For hotel or airport Wi-Fi, open Safari and visit any plain HTTP site to trigger the login page, because some networks need that before the internet works. If Wi-Fi only fails in one room, the room's distance or a wall is the cause, and moving the router or adding a mesh node is the cure; the phone's Wi-Fi signal indicator in Control Center is a rough guide, and a phone with one bar at your usual seat will drop whenever interference rises.

On a phone of the 13 Pro Max's age, a quick check is Settings, General, VPN and Device Management, where an old configuration profile from a previous employer or a free Wi-Fi app can still filter traffic and break connections. Remove profiles you do not recognize. Check also Settings, Wi-Fi, the network's info button, for Low Data Mode, which pauses background tasks and can make a connection feel slow; turn it off for your home network unless you have a data cap.