Comment 120 for bug 1752772

I have solved this for my laptop, in 2 stages.

First I installed r8168-dkms - the correct driver for my laptop. My network now appears to be up on resuming from suspend.

But I then found I could not open any DNS or IP addresses. Restarting system-resolved did not work. Restarting network-manager did not work. My laptop does run dnsmasq.

I found an answer at https://askubuntu.com/questions/1029250/ubuntu-18-04-ethernet-disconnected-after-suspend which was for an r8169.

This is an edited copy of the solution I found there:

"We need to reload the module for the Ethernet interface when resuming from suspend, after suspend. So I created script /lib/systemd/system-sleep/r8168-refresh:

#!/bin/bash

PROGNAME=$(basename "$0")
state=$1
action=$2

function log {
    logger -i -t "$PROGNAME" "$*"
}

log "Running $action $state"

if [[ $state == post ]]; then
    modprobe -r r8168 \
    && log "Removed r8168" \
    && modprobe -i r8168 \
    && log "Inserted r8168"
fi
and made it executable:

chmod +x /lib/systemd/system-sleep/r8168-refresh

The messages logged from the script will go to /var/log/syslog tagged with the name of the script and its PID. This way you can check whether the script reloaded the kernel module"

This fixed my laptop. There are other suggested ways of doing similar things in the link above.