Buffering

Help!! My speed test is less than 1 megabits per second than it will go off the scale. My provider says the service is good it is my end. This is my system:

Tp-link AX 3000 Deco x60 Whole house mesh system

Calix Giga point 803G Model 100-04255

When i unplugged router and restart i have excellent speed. Any suggestions? Thanks