chelsio t420

Hi, I have a strange trouble on my home lab. I have two Chelsio T420-BT on a Windows 2019 connected to two Arista DCS-7050T-64-F. The link is up for a few minutes and after the link came down. On windows, I have "Network cable unplugged". The link is up and stable if I set the speed of the port...

[WTB] 10GBe SFP+ NIC : Chelsio T520 or T420 or Intel x540 or x520 Qty 1 wanted. USA. Need Long Bracket.

Since I'm on this forum my home lab grew a little bit (doubled and tripled, lool). Normally I unload my stuff at family members, but they don't (wanna) run servers, so you get the chance. ATM the parts are located in Austria (Graz area). Insured shipping within the EU is already included...