Use your home screen to launch your settings, press general, and then press reset that is located at the bottom of the screen. Now press reset network settings.
Once you restart your iPhone, try to log in into Snapchat again.
Sometimes, to fix any major problem, you need to begin from the beginning, which means you have to uninstall the Snapchat app. Once you uninstall the app from your iPhone and then restart your iPhone. Then again reinstall Snapchat in the similar way as you would do it through the App Store. Once you reinstall the Snapchat, try to log in again. This technique works for many people.
How to fix Snapchat login issues on Android
Many Android users face these Snapchat login problems when they try to open the app, they get the standard message that says “Your Login temporarily failed, please try again after some time”
Snapchat has mentioned that the Android Snapchat users are the ones that mostly encounter these messages compared to other users. There are a few other reasons are also included for this message to appear on the phone screen of Android users. The Snapcaht suggests three things to try if you are not able to login to Snapchat.
Make sure to use only the official Snapchat app available in Google Play Store on your Android phone.
Check if your system date and clock is correct
Also, confirm that you use valid Google Account on your Android device.