iMac12,2 - Ethernet runs at 100baseTX only

[damien9158]

@tools ~ % system_profiler SPSoftwareDataType SPHardwareDataType Software:

System Software Overview:

  System Version: macOS 12.6.8 (21G725)
  Kernel Version: Darwin 21.6.0
  Boot Volume: Monterry_SSD
  Boot Mode: Normal
  Computer Name: tools
  User Name: xxx 
  Secure Virtual Memory: Enabled
  System Integrity Protection: Disabled
  Time since boot: 8 days 1:40

Hardware:

Hardware Overview:

  Model Name: iMac
  Model Identifier: iMac12,2
  Processor Name: Quad-Core Intel Core i7
  Processor Speed: 3.4 GHz
  Number of Processors: 1
  Total Number of Cores: 4
  L2 Cache (per Core): 256 KB
  L3 Cache: 8 MB
  Hyper-Threading Technology: Enabled
  Memory: 16 GB
  System Firmware Version: IM121.004F.B00
  OS Loader Version: 540.120.3~22
  SMC Version (system): 1.72f2
  Serial Number (system): D25HF09QDHJW
  Hardware UUID: FA3AB7DF-69A6-5F96-942A-33D72D997127
  Provisioning UDID: FA3AB7DF-69A6-5F96-942A-33D72D997127

Ethernet:

Broadcom 57765-B0:

  Bus: PCI
  Vendor ID: 0x14e4
  Device ID: 0x16b4
  Subsystem Vendor ID: 0x14e4
  Subsystem ID: 0x16b4
  Revision ID: 0x0010
  PCIe Link Speed: 2.5 GT/s
  PCIe Link Width: x1
  Driver: com.apple.iokit.CatalinaBCM5701Ethernet
  BSD Device Name: en0
  MAC Address: 40:6c:8f:04:b8:fd
  AVB Support: No
  Maximum Link Speed: 1 Gb/s

damien@tools ~ % ifconfig en0 en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500 options=50b<RXCSUM,TXCSUM,VLAN_HWTAGGING,AV,CHANNEL_IO> ether 40:6c:8f:04:b8:fd inet6 fe80::1c62:4f5c:8d42:23f%en0 prefixlen 64 secured scopeid 0x6 inet 192.168.xx.xx netmask 0xffffff00 broadcast 192.168.xx.xx nd6 options=201<PERFORMNUD,DAD> media: autoselect (100baseTX <full-duplex,flow-control>) <<<< ---- Doesn't run at supported 1000baseT status: active