One day, after a thunderstorm, the Ethernet port in the DSE7420MK2 generator control module stopped working. The link appeared and disappeared, but at a distance of 10m the device was not accessible. If you connect with a short 1m cable, then sometimes it was available.
Although the device was indoors and grounded, static electricity still damaged the device during a thunderstorm.
To solve the problem, I ordered a KSZ8081RNBIA chip on Aliexpress, which cost $1.5 and after replacing it, the Ethernet port in the DSE7420MK2 generator control module began to work perfectly.
To prevent a similar situation from happening again, an optical fiber was installed to the device and a GPON ONU was connected to it.
See also my article:
SNMP OID for DSE 7420 MKII