How does a router affect my ISP's internet speed?

Question

network hardware

I live with a very sad Internet - 2 Mbps (the most expensive tariff plan, oh yes). There are 2 connection options - open Wi-Fi with VPN authorization (without it, it only allows access to the Internet to the local domain) and a cable with PPPoE. Through them, the speed is usually ~ 1.8 Mbps.
However, there is a very strange moment with the router. If the connection goes through it, then the output is 20-30 Mbps, contrary to the two prescribed by the tariff. Why is this and is it possible to achieve such a result directly, i.e. on an Ubuntu laptop?

Answer 1

Maybe you caught someone else's Wi-Fi :D

Answer 2

1) Compare the speed not through Speedtest, 2ip and other puzomerki, but by honestly downloading a large file from mirror.yandex.ru
2) Use the "tracert -d ya.ru" console command to check the routes when connecting directly and through a router. Should differ only in the presence or absence of a router in the first line.