That's what I expected, as well.
Unfortunately, a direct connection between the Mac and the Pace router always hung unless I manually forced the Mac all the way down to 10baseT speeds (~9 Mb/s). Even then, the connection was unreliable (and my monitors would sometimes flicker--Thunderbolt hiccup?). I would have expected the router and the Mac to auto connect at 1000baseT and function normally at ~1 Gb/s.
If you've read this far here are a few more details: First, I replaced the cables with cat 6 or better, even though the run is less than 1 meter. When directly connected, the Mac would auto detect the router and set itself at 100BaseT and the router would also auto detect indicating 100BaseT, even though they should have connected at 1000BaseT. Typically the Mac would slowly indicate some kind of a connection and the DHCP would eventially load. Despite the indication of a connection, no data could be sent to/from the internet. Manually setting the router or the Mac to any speed except 10BaseT resulted in no functioning ethernet internet connection. In addition to changing the speeds on the Mac ethernet port, I tried different flow control options (and other parameters) but these seemed always to auto-revert to the baseline full-duplex despite being in manual mode.
When I took the Mac to the Apple Store and we connected it via ethernet to the internet, the Mac worked properly, auto connecting at 1000BaseT speeds. When I brought the Mac back home and reconnected it directly to the Pace router, no joy. I then connected the Mac to one of my peripheral mesh routers where the Mac ethernet connection also worked perfectly, like at the Apple Store. I then picked up an inexpensive 1GB switch and placed it between the Mac and the router and all seems to be working, so far.
