I may have follow wrong your mentioned guide, I will do it again tomorrow
I've just installed a old version
www.linuxcnc.org/testing-stretch-rtpreem...-uspace-i386-r13.iso
It worked like charm doing a ping with the 7i97 !!!!!
arnoldo@debian:~$ ping 192.168.1.121
PING 192.168.1.121 (192.168.1.121): 56 data bytes
64 bytes from 192.168.1.121: icmp_seq=0 ttl=64 time=0.200 ms
64 bytes from 192.168.1.121: icmp_seq=1 ttl=64 time=0.226 ms
64 bytes from 192.168.1.121: icmp_seq=2 ttl=64 time=0.231 ms
64 bytes from 192.168.1.121: icmp_seq=3 ttl=64 time=0.227 ms
64 bytes from 192.168.1.121: icmp_seq=4 ttl=64 time=0.264 ms
64 bytes from 192.168.1.121: icmp_seq=5 ttl=64 time=0.226 ms
64 bytes from 192.168.1.121: icmp_seq=6 ttl=64 time=0.227 ms
64 bytes from 192.168.1.121: icmp_seq=7 ttl=64 time=0.225 ms
64 bytes from 192.168.1.121: icmp_seq=8 ttl=64 time=0.226 ms
64 bytes from 192.168.1.121: icmp_seq=9 ttl=64 time=0.230 ms
64 bytes from 192.168.1.121: icmp_seq=10 ttl=64 time=0.229 ms
64 bytes from 192.168.1.121: icmp_seq=11 ttl=64 time=0.234 ms
64 bytes from 192.168.1.121: icmp_seq=12 ttl=64 time=0.227 ms
64 bytes from 192.168.1.121: icmp_seq=13 ttl=64 time=0.226 ms
^C--- 192.168.1.121 ping statistics ---
14 packets transmitted, 14 packets received, 0% packet loss
round-trip min/avg/max/stddev = 0.200/0.228/0.264/0.000 ms
arnoldo@debian:~$
This old version let me use the graphical edit tool for configuration of the connection. The new version was just impossible.
Many thanks for the help!