When you say you were "always able to select MTU 9000", are you referring to Network Settings on the Hackintosh? The paragraph below states that MTU will not "stick" whether selected from the pop-up menu or entered as a manual value.
Are the screenshots for (a) WiFi or (b) Wired Ethernet? Or the same inability to set jumbo frames applies to both?
It's fairly common to use jumbo frames for communication with NAS so I agree it's desirable to find a solution.
So this issue happens with a Chelsio T4 PCIe card? Does it have an Aquantia or Intel or some other controller?
Thanks for the attention, much appreciated! For clarity, on the wired Chelsio Nic’s (I have 5 or 6 of them T4, T5, and T6), when I navigate to advanced network settings (as pictured), auto configuration doesn’t allow the selection of 9000 MTU, it’s not a visible selection, only 1500 MTU is selectable. To change MTU, I have to select manual configuration, autoselect speed, then I am able to choose either 1500 MTU, 9000 MTU, or Custom. Selecting 1500 MTU, there are zero detectable issues. If I select 9000 MTU, it sticks, but Finder often freezes when connecting to an SMB share, requires restart, slow network performance, if I can connect to an SmB share - a transfer will start at pace, halt for up to 30-45 seconds, sometimes drop the connection, sometimes it will get going again and finish the transfer, this behavior is not predictable, however more often than not, I get finder freezing then restart. Additionally, in any browser, I’m able to connect to internet just fine, no issues, but nearly every LAN destination will fail to load. So, we’ve got finder freezing, dropped SmB and iscsi connections, start/halt/resume file transfers, inaccessible LAN sites. Back to settings, when I select custom MTU I can type in 9000 MTU, hit save, then apply changes, but the changes don’t stick, it reverts back to 1500 MTU no matter what.
because the problematic network behavior only occurs when selecting 9000 MTU, Ive concluded that is the issue.
it occurs on all Chelsea interfaces that I have, all models. However, the same behavior can’t be replicated on either of my two Apple Macs. Works fine on genuine Apple, to select 9000 MTU, same exact setup.
i checked today, and amazon seems to be opening up some more, so I can get an aquantia NIC by Sunday, which I’ll likely do, just to test.
it’s just very bizarre, I was on Catalina for months without any issue with jumbo frames and the Chelsea NIC’S. It just began a week or so ago, out of the blue.