Does your ISP cut your internet speed?

Question

Computer networks

When checking for SpeedTest, it gives out normal speed both through the router and directly through the cable. But when checking packet losses (through a cable and a router, no difference) with a command
ping -l 15000 -n 50
with -l values ​​\u200b\u200bhigher than 15000, losses begin. Does this mean that the provider deliberately cuts the sending of "large" packets? With -l 10000, everything is sent normally.

Answer 1

It is quite possible that pings with such a packet size are stupidly cut, simply because there is no need to send them like that - thus there is nothing reasonable to check ... And this is not connected with the speed limit.
Ping is generally not suitable for testing the bandwidth, only for testing losses and delays between points.
There are other tools to test the band, such as iperf, but it requires some other side with a known wide channel.

Answer 2

Providers absolutely always "cut" the speed, because they need to distribute the channel width among users in accordance with their tariffs. And what you showed is the brakes of the provider's router. Do you have Ethernet to the apartment?