Hi. I see that it is quite while since you posted your Intel Ethernet Controller 1225 experience.
I had the same with a ASUS ROG STRIX B550-E GAMING I bought fall last year (2022). The ENet connection was working, but sometimes lost connection and it was difficult to get it back to work. Sometimes it was not even possible to restart the Ethernet Adapter (Code 10) and I had to use wireless.
I received the board with Firmware ROG STRIX B550-E GAMING BIOS 2803. I use an AMD Ryzen 5 5600X CPU. I experienced the problem as described until ROG STRIX B550-E GAMING BIOS 3002. Yesterday I found, that there is a new BIOS version: ROG STRIX B550-E GAMING BIOS 3202.
I updatet the BIOS to this version (3202). Guess what: My Ethernet connection works now absolutel perfect! All problems are gone!
Now i'm absolutely happy with this powerful board
I hope this is helpfull to anybody who is having the same difficulties