10GB Ethernet:
The Mac Studio has a 10GB Ethernet port. If you have some fancy equipment at the other end of the cable, it is possible it is trying to make a 10GB connection.
A 10GB (or 5GB or 2.5GB) connection is only stable when cables are excellent and fairly short (like Category-6 rated cables under 100 feet). If either of those are not true, or you have you added patch cables that are not Category-6 rated, you could be seeing it connect at a faster-than-Gigabit speed, then error out and disconnect.
Actual Speed:
The good way to check the actual connection speed USED to be Network Utility, But in Big Sur and later, Apple has deprecated network Utility and now you have to use a Terminal command to see your actual connection speed. First, you need to know what en number the link is. then you use a command like this one, substituting the actual en number.
my main Ethernet connection uses BSD name en5 (as shown in) :
menu > about this Mac > (system report) > network:
ifconfig en5 | grep media
with this as my output:
media: autoselect (10Gbase-T <full-duplex,flow-control>)
For Gigabit Ethernet, you should get this instead:
media: 1000baseT <full-duplex,flow-control>
Errors detected:
To see if an Ethernet link is throwing more than a handful of initial errors, you can use Terminal command:
netstat -I en5
This is the resulting output. Counters are In-packets, In-errors, Out-packets, Out-Errors, Collisions. There should never be more than handful of errors from starting up, and in most cases, NONE.
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll
en5 8163 <Link#4> 00:01:d2:1a:00:dd 696697 0 484301 0 0
en5 8163 grantsmacpr fe80:4::461:ea0d: 696697 - 484301 - -
en5 8163 192.168.0/23 192.168.0.204 696697 - 484301 - -
If the link were running beyond its ability to run and be stable, for example it auto-speeded to 10GB but the cabling could only reliably support 2.5GB, we would see non-zero errors counts, and errors increasing over time. (and possibly, disconnecting)
