s8 plus 4g network issue

It looks like you are already on 4g and you posted this post and that means its working

I contacted jio customer care.

Solution:

Dear Customer,
Here is a step-by-step guide on How to Restore or Reset APN Settings?>Swipe finger up or down>Settings>Connections>Mobile networks>Access Point Names>SIM 1 or SIM 2 tab>Tap on Menu>Reset to default>RESET

Thank you,
Team Jio

Restart after these steps..

it's not working

Thanks for being with Samsung and sharing your concern. We would like to inform you that as per the above attachment your device is already connecting with 4G network so there might be internet speed issue please coordinate with Service provider. Be sure to hit ♡ when you find an answer that works for you.