Rote LED

rtt min/avg/max/mdev = 0.085/0.161/3.281/0.042 ms

is better but still not good

Take a look at this thread, especially the kernel command line (setup with grub)

forum.linuxcnc.org/18-computer/56380-error-finishing-read-sigh
 

Hallo ich habe wieder einen Fehler, anderer Rechner AMD 3500
Mit Realtec Chipsatz, DKMS Treiber installiert. Ehternet Verbindung steigt mitten im Programm aus. Was kann ich noch tun

60000 packets transmitted, 59995 received, +5 errors, 0.00833333% packet loss, time 60033ms
rtt min/avg/max/mdev = 0.052/0.106/0.265/0.030 ms, pipe 2

Not sure why you are getting dropped packets, might be hardware related
though the NUC didn't drop packets. 

Try another network cable, kinked or nicked or stepped on cables can cause issues. Also some cheap cables will cause a lot of headaches, sometimes even not so cheap ones as i had a brand new never used cable that would absolutely not connect to Mesa. I did cut it into many tiny pieces Over 30 of the same brand worked fine.

Neues Kabel gleicher fehler

-- 10.10.10.10 ping statistics ---
60000 packets transmitted, 59993 received, +6 errors, 0.0116667% packet loss, time 60036ms
rtt min/avg/max/mdev = 0.054/0.110/0.313/0.031 ms, pipe 12

Was gibt beim
ip a
in terminal?

Is there some other device you can ping to see if the issue is the host or the FPGA card?

Hallo ich habe den Test an 2 Verschiedenen Mesa ausgeführt

No idea why packets are being dropped, its unlikely that you have two bad Mesa cards
(and its an odd symptom) 

Didn't you have another PC that did not drop packets?

I would not expect any packet loss even in weeks of operation, here's 10 minutes with a 7I96S

peter@peter-HP-EliteDesk-800-G1-USDT:~/linuxcnc/configs$ sudo chrt 99 ping -i .001 -c 600000 -q 10.10.10.10
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.

--- 10.10.10.10 ping statistics ---
600000 packets transmitted, 600000 received, 0% packet loss, time 599999ms
rtt min/avg/max/mdev = 0.105/0.108/0.208/0.003 ms

 

Are the Mesa boards wired directly to the PC?
meaning no switches or hubs or routers or access points.