Realtek driver doesnt work when network is on lower speed

[Vesa Suontama]

I have " Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 02)"
but network doesn't work unless I manually run

sudo ethtool -s enp6s0 autoneg off speed 10 duplex full

It seems like the speed gets auto negotiated incorrectly.

Very often the cable is reported unplugged, or somtimes it is reported connected, but no packets fly.

After running the ethtool it works, but the command has to be re-run always e.g. after wakeup after suspend. Is there a way to force the network speed?

Network may work, if the system has been off for a long time, but after suspend it never works.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: network-manager 1.0.4-0ubuntu5.3
ProcVersionSignature: Ubuntu 4.2.0-34.39-generic 4.2.8-ckt4
Uname: Linux 4.2.0-34-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
Date: Wed Apr 6 23:40:02 2016
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2016-03-24 (13 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
IpRoute:
 default via 192.168.1.254 dev enp6s0 proto static metric 100
 169.254.0.0/16 dev enp6s0 scope link metric 1000
 192.168.1.0/24 dev enp6s0 proto kernel scope link src 192.168.1.70 metric 100
IwConfig:
 enp6s0 no wireless extensions.

 lo no wireless extensions.
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
RfKill:

SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.NetworkManager.NetworkManager.conf: 2016-04-05T19:19:11.830221
nmcli-con:
 NAME UUID TYPE TIMESTAMP TIMESTAMP-REAL AUTOCONNECT AUTOCONNECT-PRIORITY READONLY DBUS-PATH ACTIVE DEVICE STATE ACTIVE-PATH
 Wired connection 1 16a35d98-f5c4-4aad-970b-d1a0e9f9de1a 802-3-ethernet 1459974988 ke 6. huhtikuuta 2016 23.36.28 yes 0 no /org/freedesktop/NetworkManager/Settings/0 yes enp6s0 activated /org/freedesktop/NetworkManager/ActiveConnection/14
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 enp6s0 ethernet connected /org/freedesktop/NetworkManager/Devices/0 Wired connection 1 16a35d98-f5c4-4aad-970b-d1a0e9f9de1a /org/freedesktop/NetworkManager/ActiveConnection/14
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/1 -- -- --
nmcli-nm: Error: command ['nmcli', '-f', 'all', 'nm'] failed with exit code 2: Error: Object 'nm' is unknown, try 'nmcli help'.