If you cannot find a record of your password (as indicated, it's a good idea to have passwords written or recorded somewhere), one thing you could do is make sure your new i-phone is set up as a new device i.e. a different name. That should be considered a new device and you should be able to set up a new share to your camera.
Its also possible to reset the network settings on the camera, which will treat a connection to a new device as new.
Bay Area - CA
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I agree. You need to clear out the network connection to the old phone. It only works with that phone’s MAC address. You need to define a new connection to the new phone’s MAC address.