@Andrew I bought a RTL8126 5G card (because of the price) for my home lab that doesn't appear to be working with 8.3 like you said. It is trying to use the r8125 driver.

[08:53 tw-xcp-ng-02 ~]# ethtool -i eth2
driver: r8125
version: 9.012.04-NAPI-PTP-RSS
firmware-version: 
expansion-rom-version: 
bus-info: 0000:02:00.0
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: yes
supports-priv-flags: no

I removed the r8125 driver and manually installed the r8126 driver which I downloaded from here. I can see the interface using the driver, and it shows the 5G capabilities of the driver, however I cannot get this to negotiate the speed (see below). I have tried this with a 2.5G switch and a 10G switch. The 10G switch can negotiate down to 5G so that shouldn't be an issue. On both switches it shows its connection as just fast ethernet. If I manually set the port on the switch to 5G I will not even get a link light.

Would you happen to have any suggestions or ideas to get the card working?

[09:49 tw-xcp-ng-02 ~]# ethtool -i eth2
driver: r8126
version: 10.015.00-NAPI
firmware-version: 
expansion-rom-version: 
bus-info: 0000:02:00.0
supports-statistics: yes
supports-test: no
supports-eeprom-access: no
supports-register-dump: yes
supports-priv-flags: no

[09:46 tw-xcp-ng-02 ~]# ethtool eth2
Settings for eth2:
	Supported ports: [ TP ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Full 
	                        2500baseX/Full 
	                        2500baseT/Full 
	                        5000baseT/Full 
	Supported pause frame use: Symmetric Receive-only
	Supports auto-negotiation: Yes
	Supported FEC modes: Not reported
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	                        1000baseT/Half 1000baseT/Full 
	                        2500baseX/Full 
	                        2500baseT/Full 
	                        5000baseT/Full 
	Advertised pause frame use: No
	Advertised auto-negotiation: Yes
	Advertised FEC modes: Not reported
	Speed: Unknown!
	Duplex: Unknown! (255)
	Port: Twisted Pair
	PHYAD: 0
	Transceiver: internal
	Auto-negotiation: on
	MDI-X: on
	Supports Wake-on: pumbg
	Wake-on: d
	Current message level: 0x00000033 (51)
			       drv probe ifdown ifup
	Link detected: no

[09:52 tw-xcp-ng-02 ~]# lspci | grep Ethernet
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (17) I219-LM (rev 11)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. Device 8126 (rev 01)
03:00.0 Ethernet controller: Intel Corporation Ethernet Controller I225-V (rev 03)

@olivierlambert It just shows that people are passionate about this project.

In the end you cannot make everyone happy, but since you are seeking feedback I will provide my 2 cents.

@olivierlambert I like this one the best so far. I like how there is a lot less red, but still some there.