[...]
[455046.082705] bcmgenet fd580000.ethernet eth0: Link is Down
[455047.122705] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[456476.109203] bcmgenet fd580000.ethernet eth0: Link is Down
[456477.149350] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[456893.155419] bcmgenet fd580000.ethernet eth0: Link is Down
[456894.195524] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[459543.126120] bcmgenet fd580000.ethernet eth0: Link is Down
[459545.206276] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[461559.729729] bcmgenet fd580000.ethernet eth0: Link is Down
[461560.769823] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[462142.125267] bcmgenet fd580000.ethernet eth0: Link is Down
[462143.165382] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[464104.654740] bcmgenet fd580000.ethernet eth0: Link is Down
[464106.734737] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[490920.530567] bcmgenet fd580000.ethernet eth0: Link is Down
[490922.610699] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
[492002.148230] bcmgenet fd580000.ethernet eth0: Link is Down
[492003.188354] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
Wifi off, dynamic IP address, connected to router/DHCP server via switch, 3A power supply
A RPi 4 has GbE and a proper installation would negotiate to use it.
That isn’t an issue with standard openHABian let alone openHAB but with your networking setup and/or hardware. You need to provide networking details and what you have analyzed and tried so far if you want others to help you; strictly speaking you should go looking for help elsewhere on some networking forum. Please at least change to use proper tagging on your post.
Try different port on switch?
Tried different cable to device?
Tried setting port on switch to 1 GB full and not auto negotiate?
That would be my first questions.
Thanks for all constructive suggestions. The switch is a 100 Mbit/s switch, so the message from the Ethernet driver doesn’t necessarily indicate a handshake problem - sorry for not mentioning the switch parameters.
Let’s replace the onboard Ethernet controller with an external one:
[583159.920161] usb 2-2: new SuperSpeed USB device number 2 using xhci_hcd
[583159.956953] usb 2-2: New USB device found, idVendor=0b95, idProduct=1790, bcdDevice= 1.00
[583159.956983] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[583159.957005] usb 2-2: Product: AX88179
[583159.957023] usb 2-2: Manufacturer: ASIX Elec. Corp.
[583159.957040] usb 2-2: SerialNumber: 0000000000006C
[583160.318947] ax88179_178a 2-2:1.0 eth1: register 'ax88179_178a' at usb-0000:01:00.0-2, ASIX AX88179 USB 3.0 Gigabit Ethernet, 00:0e:c6:d9:d4:35
[583160.398661] systemd-udevd[22937]: Using default interface naming scheme 'v247'.
[583507.153048] bcmgenet fd580000.ethernet eth0: Link is Down
[583514.941736] ax88179_178a 2-2:1.0 eth1: ax88179 - Link status is: 1
[583514.948846] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
So far no flaps on eth1 - but it is too premature for a final conclusion. Stay tuned.
Glad you got it stable.
For me and my curiosity to fully understand root cause when things misbehave, I would dig out a 1 gigabyte switch and test with it to see if the onboard ethernet controller is only funky when negotiating a 100-megabyte connection. just because I have seen that kind of weirdness in the past with the some of the lower end chipsets (knock offs) a few years ago.