@cmb:
@NotAnAlias:
I believe I am experiencing the same issue. When I upload to youtube, my internet packetloss is around 50%. It is only with youtube, nothing else.
It looks like pfsense's network graph doesn't handle it well either. It reports the wrong bandwidth being used.
In that case it looks like QUIC's congestion control is broken.
The graph is absolutely correct, that uses the NIC's counters. You can pass more traffic out of an interface than your ISP allows. The only limit to how much you can push out your WAN NIC is its link speed, probably 100 Mb or 1 Gb. TCP won't exceed your ISP-imposed speed limit because of its congestion control. UDP has no such congestion control so you can blast as much as you want, but everything past your connection's upload limit will be dropped upstream. QUIC congestion control is supposed to prevent sending more traffic than your link allows. Since it's not, it can overrun your connection so much it will result in significant problems.
That's the fun part of networking: slowest link matters. You have a gig to your pfSense box, 100 to the cable modem, then the other side of that is clamped to 25 upstream. Almost makes one want to put in a queue for outbound traffic clamped to the 25Mbps.