Most likely the packet scheduling, I suppose the mpctp kernel module has sometimes to wait to get all packets in the right order.
Also, I am aggregating 2 4G link which might not help since both links send large packets of data infrequently if I understand correctly. Maybe aggregating 2 wired link would have lower increased latency cost.
In the end, I'm getting up to 40Mbits of bandwidth instead of being stuck with my 3MBits adsl link and I'm pretty happy.
that is actually somewhat impressive performance in my books. i would guess 4G links are inherently unstable regarding prediction of connection characteristics for proper scheduling... thanks for sharing your experience with that :)
Also, I am aggregating 2 4G link which might not help since both links send large packets of data infrequently if I understand correctly. Maybe aggregating 2 wired link would have lower increased latency cost.
In the end, I'm getting up to 40Mbits of bandwidth instead of being stuck with my 3MBits adsl link and I'm pretty happy.