Very poor internet speed on the phone, is everything fine on other devices?

Question

Android

There is a router with an input of 100 Mbps, 4 devices (1 of them is a telephone).
While on laptops 90-100 Mbps, on the phone 10 Mbps (and 20 Mbps output).
I reflashed it (to different firmware), updated it, there is no VPN.
What to do?
Zuk z1, Lineage OS 16

Answer 1

The laptop is larger than the phone, which means the antenna is larger. More battery means more power. Therefore, the laptop wins the fight for the air. Both the second and the third. Only crumbs remain for a small telephone.

Answer 2

reset phone try