2020 13" MBP 10.15.5 w/Razer Core X Chroma (ASIX AX88179 v2.16) ethernet issues.
Unfortunately, like others here it seems ethernet issues may persist with MacOS and the Razer Core X Chroma. I didn't know about the issues prior to buying and installing but when I installed I went straight to v2.16 via Homebrew `brew cask install asix-ax88179` (tap homebrew/cask-drivers) since I noticed Razer's download was for ASIX OEM driver v2.14.
My current set up is with a Radeon RX 5700 XT, the 2020 MBP 13" is a four TB3 model, the laptop is connected via Razer's provided 0.7m passive-TB3 cable, the Core X CAT6 is wired directly to a Synology RT2600AC, the other USB devices connected (Magic Keyboard, Logitech mouse, Creative E5 DAC/AMP) all work without issue. The GPU itself seems to work without issue as well.
Running speedtest[.]net seems to be enough to cause the ethernet connection to drop, it fails, DNS queries fail, and the upload portion of the test fails. Reseat the CAT6, refresh, run the test again, fails again.
At this point, it seems the Razer Core X might be the better/more reliable Razer eGPU option for MacOS users despite the need for an additional USB-C/TB3 dock.
Any chance you could try it on a TB3 PC? Considering everything else appears okay except for ethernet, could well be a hardware issue with that particular unit only.
Also, depending on your network setup, i'd try connecting the Core X ethernet directly into your modem. I've seen Synology's cause some very bizarre and unforeseen things before, i would try and remove as much network equipment between the Core X and the internet, from the equation as possible.
It looks like ASIX has released v2.17.0 drivers, dated 2020-06-19 but they must've RTW 2020-07-07:
I will definitely install those and update with results.
I decided to start going the other route, swapping for a non-Chroma with a dock (ideally daisy chained for single cable convenience despite any perf hit). So I ended up buying a Belkin Thunderbolt 3 Dock Pro, testing now, everything seems to be working well. I also considered OWC's 14-port TB3 dock, looks like it might also be a reasonable option along with CalDigit. OWC is nice enough to even mention the chipsets used in the dock.
Anyway, with the Belkin and Chroma combo: all 4 USB devices work, ethernet shows up as USB 10/100/1000 LAN in System Report and the connection is stable, the Core X Chroma eGPU is daisy-chained via the TB3 downstream port and that appears stable as well.
Any chance you could try it on a TB3 PC?
Unfortunately no, my PC has a MSI X99A motherboard without TB3.
i'd try connecting the Core X ethernet directly into your modem
When the connection is dropped all network traffic is dropped, it's as if the cable is no longer connected. I didn't test with the modem since the Speedtest was enough to trigger things as was a large file transfer to my old MBP. I did test and confirm a system to system connection fails.
Will have to see about those new drivers from ASIX.
The new v2.17.0 drivers did nothing to improve the connection drop. I had my nephew bring his 2017 15" MBP by and we tested various connection scenarios, same result.
I can be pinging a machine on the LAN via IP and either a large file transfer or speed test will cause the connection to fail. Renewing the IP fails, reseating the cable resolves things temporarily.