Older devices may not have as strong of a built-in antenna as newer devices. This means you may experience mobile data errors far more often. You can buy smartphone antennas that attach via the auxiliary/headphone port, but they usually don't work that well.
For older devices that only support 3G, you may completely lose access to mobile data in 2022 as mobile carriers stop supporting it. If you want to continue using your device, you'll need to switch to Wi-Fi. Once on Wi-Fi, you can also link your Android device to your Windows PC.