It is not a big deal if you are dealing with the problem of Gmail not working on iphone mail app as this problem could be solved very easily by the users as it will not only help you with the ways to fix the problem step by step properly for you.
Ways to fix the problem of Gmail not working on iPhone –
You should first try to login into the Gmail account and then look if you have got any alerts on Gmail or any other alerts which you need to fix.
In this method you can reset the CAPTCHA for your Gmail so that you are not facing the problem of Gmail app not working on iphone for you.
Another reason because of which your Gmail might not be working is because of the IMAP, it could be possible that you have not enabled the option of IMAP on your Gmail app or server. So, make sure that you have now turned on the IMAP for Gmail on your device.
Another troubleshooting method you can try on your device is that you can first remove your account and then you can add it again on your device using the login credentials of your account. It could be possible that you might be able to fix the issue of Gmail not working on iphone so that you can use its services without any troubles and issues for the same. We also hope that by following and executing the steps which we have provided you were helpful for you and you were able to fix your problem by following it.