@Sunshine when I use only 3g , internet not working.

@Sunshinemostly it stays on 4g but sometimes it go to 3g. But it is a rear incident.

I have 2 tp link router tl-mr6500v . I have a airtel sim . Though internet is well working but calling feture isn't working on both router. In settings-network is 4g preferred, volte enabled in both...