Hello malloyca,
Welcome to Apple Support Communities.
We understand that your Apple devices will sometimes forget the Wi-Fi passwords and you have to reenter them. We are happy to help.
Are you using the same Apple ID on all of your devices? Have you made any recent changes to your devices? Have you recently changed Internet Service Providers? Does your router and modem require a firmware update? If so, you may need to contact your Internet Service Provider to assist you with the this. Are you using a particular app(s) when this occurs? These answers will help us to further isolate the cause.
Apple recommends these settings. Please apply these settings as they may help: Recommended settings for Wi-Fi routers and access points - Apple Support
"Router settings
To ensure that your devices can connect securely and reliably to your network, apply these settings consistently to each Wi-Fi router and access point, and to each band of a dual-band, tri-band, or other multiband router. Before changing the settings, you should take these steps:
- Back up your existing settings, in case you need to restore them.
- Install the latest firmware updates for your router. This is generally done from the app or webpage that you use to administer the router.
- Update the software on your other devices, such as on your Mac and on your iPhone or iPad, to ensure that they have the latest security updates and work best with each other.
After changing the settings, you might need to forget the network on each device that previously joined the network. This ensures that the device uses the router's new settings when rejoining the network."
We also recommend that you check for potential signs of Wi-Fi interference: Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support
"How to reduce wireless interference
These general steps can help achieve a cleaner, stronger wireless signal:
- Bring your Wi-Fi device closer to your Wi-Fi router. Bring the Bluetooth devices that are connecting to each other closer together.
- Avoid using your wireless devices near common sources of interference, such as power cables, microwave ovens, fluorescent lights, wireless video cameras, and cordless phones.
- Reduce the number of active devices that use the same wireless frequency band. Both Bluetooth and Wi-Fi devices use the 2.4 GHz band, but many Wi-Fi devices can use the 5 GHz band instead. If your Wi-Fi router supports both bands, it might help to connect more of your Wi-Fi devices to the 5GHz band. Some dual-band routers manage this for you automatically.
- Configure your Wi-Fi router to use a different Wi-Fi channel, or have it scan for the channel with the least interference. Most routers perform this scan automatically on startup or when reset.
If you're using USB 3 or Thunderbolt 3 devices with your computer, you can limit their potential to interfere with nearby wireless devices:
- Use a high-quality, shielded USB or Thunderbolt 3 cable with each device.
- Move your USB 3 or Thunderbolt 3 devices—including any USB hubs—farther away from your wireless devices.
- Avoid placing USB 3 or Thunderbolt 3 devices on top of your Mac.
- Turn off any USB 3 devices that aren't in use.
Avoid physical obstructions in the path of your wireless signal. For example, a metal surface between your Bluetooth mouse and computer could cause the mouse to perform poorly, and a metal-reinforced concrete floor between your Wi-Fi router and Wi-Fi device could cause poor Wi-Fi performance.
- Low interference potential: wood, glass, and many synthetic materials
- Medium interference potential: water, bricks, marble
- High interference potential: plaster, concrete, bulletproof glass
- Very high interference potential: metal"
Let us know if you have further questions.
Take care.