Nothing speaks against having the traffic go out of the interface at 1Gbit/s
into the switch.
The idea behind not doing that, is that you want to "own the queue."
On upstream to a modem, having 1Mb/s upload speed, ethernet speed is way faster. Packets sent out to modem with higher rate than 1Mb/s will be queued in modem. Indeed TCP can handle this.
But all outgoing packets will have to wait in line on that queue, adding a delay of 2000mS to all of them. (and excess packets get dumped).
The idea of shaper is, that you want to control this yourself.
Your code snippet, did you apply it to an interface? On speedtest, overall throughput should become lower, but latency should be way better
