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I was recently provided with a 2018 MBP by my employer. The network throughput slows gradually until I'm forced to reboot.
The following machines are connected via wired ethernet to a gigabit switch:
- 2018 MBP (the problematic machine, 10.14.4)
- 2015 MBP (the control, thunderbolt ethernet adapter, 10.14.4)
- 2010 iMac (the test target, built in ethernet, ubuntu)
The 2018 MBP has a usbc-thunderbolt adapter, with a thunderbolt display attached and the ethernet cable connected to the display.
When the throughput drops, I've tried the following:
- Switch to WiFi - doesn't help, speed starts off around 300MBit/s but drops to the level the wired connection is currently at.
- Use a different switch port / ethernet cable - doesn't help
- Test speed on control MBP using 2018 MBP's ethernet cable & switch port (it's fine)
- Connect thunderbolt monitor to control MBP and test throughput (also fine)
- Disconnect usbc-thunderbolt adapter incase it's doing something odd (no difference)
- Disconnect power from 2018 MBP (no difference)
- Sleep/Wake 2018 MBP (no difference)
I setup a test to show the problem: rebooted the 2018 MBP then looped iPerf making connections to the iMac and plotted the results, sure enough after a couple of days I'm getting 10MBits/s across a gigabit switch:
The problem isn't the iMac (test target) as I also made periodic tests from the control MBP to the iMac which consistently showed ~940Mbits/s.
I've been using the 2015 MBP and thunderbolt display with it's ethernet connection for years without issue, and have ruled that out as a cause. Also WiFi shows the same problem, which suggests its not related to a specific interface. I suspect a software problem with the networking stack on the 2018.
Potentially suspicious software:
- Symantec Endpoint Protection (mandated by employer)
- Pulse Secure (required for VPN connection to employer, but not connected during these tests)
- Docker (required for development, does add bridges etc to local networking - this doesn't cause a problem on the 2015 MBP though.)
- Any idea what this might be about?
- Is there any way to reset the networking stack or some workaround that doesn't involve a reboot?
Unfortunately removing SEP is not an option :(