I have a 2018 MacBook Pro i7 running MacOS Catalina 10.15.3. I'm uploading a 4.88 GB video to YouTube, using the YouTube Studio web interface in Google Chrome 79. My MacBook Pro is connected to my 5 Ghz SSID on my TP-Link EAP245 (Generation 1) access point, which is connected via gigabit ethernet to my Ubiquiti EdgeRouter X, which connects to my Netgear CM1000 cable modem. I don't have any VLANs or special routing rules configured.
According to the Network tab of Activity Monitor, I'm uploading data at roughly 10 megabytes per second (MB/sec). However, my Internet service is only supposed to support 35 megabits per second (Mb/sec), which comes out to about 3.5 megabytes per second.
I'm reasonably confident that there is no other major data transfer occurring in parallel with my YouTube video upload.
I can use the Python-based
glances utility to observe that only a single network interface (my
en0 Wi-Fi adapter) is pushing out approximately ~80 Mb/sec, which roughly matches the 10 MB/sec. that I'm seeing in Activity Monitor. When I'm not uploading a video, the idle utilization of the
en0 network interface is only a few KB/sec.
en0 network interface is using the default MTU of 1500, according to
ifconfig. All my other network devices use the default MTU.
In addition, according to my router's traffic monitor, I'm actually pushing out 44 Mbps (35 Mbps slightly over-provisioned).
Question: How can I explain the discrepancy between a 3.5 MB/sec. Internet service, versus the ~10 MB/sec being indicated by Activity Monitor in MacOS?