my phone is samsung m30s 4/64 4 month old

[Samsung_OYF5KFz]

The net is running very slow in my phone while the speed of this airtel is very good

[a50sowner]

maybe signal strength is low.
1.Try other companies sim card
2.Visit areas where signal strength is high ( usually town area, tower area, balcony of house,open areas etc)

[Samsung_OYF5KFz]

I have used another sim

[Samsung_OYF5KFz]

signal strength very very high but my phone running very slow

[Ehsank]

set the network mode on auto 4g,3g,2g

[Samsung_OYF5KFz]

This is already set

[Ehsank]

you have to visit service centre