Wi-Fi speed problem

My wifi speed on phone is 10 mbps, while on every device at home, its 30 mbps.

I tried these:
Fully resetting router (TPlink)
Forgetting network and reconnecting
Clearing cache through recovery
Resetting settings

Didn't try yet:
Full factory reset, but I'll lose so much data for this.


Anything i could try?

SM-N920C