Measure the places that are frequently used and the places closest to the Internet.
In the case of the slowness of the place closest to the Internet, from the confirmation of the contract content and settings of ISP to (1) there is a problem with the line to home and leased equipment. "after re-examining the content of the contract on documents and the Internet. Contact support (2) the contract with the current ISP cannot reach a satisfactory speed. Change the ISP plan or transfer.
If somewhere in the home LAN is slow, split sequentially (3) slowly restart the Wi-Fi router first & farm update, and then cut off (4) Wired LAN slow to reinsert the cable If it still doesn't work, change it (5) Wi-Fi overall slow "re-examine Wi-Fi settings (6) slowly reconsider settings and configurations away from specific rooms or Wi-Fi routers, or import repeater (7) to confirm that only specific PC and smartphone slow settings are available. Make up your mind to change it.
There are all kinds of other problems that may cause
Even if there is no dissatisfaction with the status quo, it is possible to do it faster!?