Over the past couple of days I noticed my internet downloads were much slower than before. I investigated further and discovered my LAN connection was working at 100Base-T whereas before it had been a 1000Base-T. So reading some threads here I saw that one of the recommendations was to change the /etc/dhcpd.conf configuration from duid to clientid and then reboot. So I've tried that but since then my LAN connection has been continually flapping every 3-4 seconds. Its gotten to the stage I've had to disable it to keep the system stable, and instead use my wifi network connection. I've changed the dhcpd.conf config back to duid, and rebooted again but it has made zero difference
The only other change I've made recently that I can remember was turning off IPv6 via /etc/default/grub, and I've reversed that change (and updated grub) also and rebooted, but again it has made zero change.
The interface is set to autoneg, and get its IP via DHCP. MTU size is set to automatic, there's no 802.1x used, or anything out of the usual for a normal home network.
System is up to date with all the latest patches. Has there been an update to the e1000e driver in the past 2-3 weeks, or how do I go about figuring out whats gone wrong all of a sudden?