I was running v4.14-rc1 for the whole last week. 
It is... different.

Good stuff:
- Not a single freeze on fresh boot with dock attached.
- When it connects to eth0, it is stable. Not a single disconnect from ethernet, but that may be as well the result of recent BIOS upgrade to 1.5.0 and dock firmware update that I did at about the time I upgraded to v4.14-rc1.
- Suspend / resume stable, as long as I don't connect/disconnect the dock in the meantime.

Slightly broken stuff:
- Ethernet connection does not come up automatically after boot / login. Syslog shows the eth0 device exists, NetworkManager attempts to connect, it even gets the IP from DHCP, then it suddenly disconnects. I have to manually click in the NetworkManager icon to connect after logging into desktop and suprisingly it connects fine.

Relevant syslog fragment:
Sep 17 11:43:17 p5520 kernel: [   12.053069] usbcore: registered new
interface driver r8152
Sep 17 11:43:17 p5520 kernel: [   12.055853] usbcore: registered new
interface driver cdc_ether
Sep 17 11:43:17 p5520 tlp[1907]: Applying power save settings...done.
Sep 17 11:43:17 p5520 tlp[1907]: Setting battery charge thresholds...done.
Sep 17 11:43:17 p5520 systemd[1]: Started TLP system startup/shutdown.
Sep 17 11:43:17 p5520 systemd[1]: Startup finished in 10.048s (kernel)
+ 2.022s (userspace) = 30.839s.
Sep 17 11:43:17 p5520 set-cpufreq[1209]: Setting powersave scheduler
for all CPUs
Sep 17 11:43:17 p5520 kernel: [   12.136372] usb 4-1.2: reset
SuperSpeed USB device number 3 using xhci_hcd
Sep 17 11:43:17 p5520 kernel: [   12.265293] r8152 4-1.2:1.0 (unnamed
net_device) (uninitialized): Using pass-thru MAC addr
d4:81:d7:35:8c:11
Sep 17 11:43:17 p5520 NetworkManager[1189]: <info>  [1505641397.3556]
manager: (eth0): new Ethernet device
(/org/freedesktop/NetworkManager/Devices/2)
Sep 17 11:43:17 p5520 kernel: [   12.297452] r8152 4-1.2:1.0 eth0: v1.09.9
...
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7031]
device (eth0): link connected
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7043]
device (eth0): state change: unavailable -> disconnected (reason
'carrier-changed') [20 30 40]
Sep 17 11:43:20 p5520 kernel: [   15.645145] r8152 4-1.2:1.0 eth0: carrier on
Sep 17 11:43:20 p5520 kernel: [   15.645217] IPv6:
ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7056]
policy: auto-activating connection 'Połączenie ethernetowe 1'
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7078]
device (eth0): Activation: starting connection 'Połączenie ethernetowe
1' (e6a365af-c48e-4b8f-abd0-1ee3ea9f1a7b)
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7081]
device (eth0): state change: disconnected -> prepare (reason 'none')
[30 40 0]
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7089]
device (eth0): state change: prepare -> config (reason 'none') [40 50
0]
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7095]
device (eth0): state change: config -> ip-config (reason 'none') [50
70 0]
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7101]
dhcp4 (eth0): activation: beginning transaction (timeout in 45
seconds)
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7157]
dhcp4 (eth0): dhclient started with pid 2669
Sep 17 11:43:20 p5520 dbus[1128]: [system] Activating service
name='com.canonical.Unity.Greeter.Broadcast' (using servicehelper)
Sep 17 11:43:20 p5520 dbus[1128]: [system] Successfully activated
service 'com.canonical.Unity.Greeter.Broadcast'
Sep 17 11:43:20 p5520 dhclient[2669]: DHCPREQUEST of 192.168.0.2 on
eth0 to 255.255.255.255 port 67 (xid=0x11807b5)
Sep 17 11:43:20 p5520 dhclient[2669]: DHCPACK of 192.168.0.2 from 192.168.0.1
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   address 192.168.0.2
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   plen 24 (255.255.255.0)
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   gateway 192.168.0.1
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   server identifier 192.168.0.1
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   lease time 3600
Sep 17 11:43:20 p5520 avahi-daemon[1194]: Joining mDNS multicast group
on interface eth0.IPv4 with address 192.168.0.2.
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   hostname 'p5520'
Sep 17 11:43:20 p5520 avahi-daemon[1194]: New relevant interface
eth0.IPv4 for mDNS.
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   nameserver '62.179.1.60'
Sep 17 11:43:20 p5520 avahi-daemon[1194]: Registering new address
record for 192.168.0.2 on eth0.IPv4.
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   nameserver '62.179.1.61'
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0):   domain name 'home'
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7799]
dhcp4 (eth0): state changed unknown -> bound
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7810]
device (eth0): state change: ip-config -> ip-check (reason 'none') [70
80 0]
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7813]
device (eth0): state change: ip-check -> secondaries (reason 'none')
[80 90 0]
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7814]
manager: NetworkManager state is now CONNECTING
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7816]
policy: set 'Połączenie ethernetowe 1' (eth0) as default for IPv4
routing and DNS
Sep 17 11:43:20 p5520 nm-dispatcher: req:9 'connectivity-change': new
request (2 scripts)
Sep 17 11:43:20 p5520 systemd-resolved[1325]: Switching to DNS server
62.179.1.60 for interface eth0.
Sep 17 11:43:20 p5520 whoopsie[1589]: [11:43:20] offline
Sep 17 11:43:20 p5520 dhclient[2669]: bound to 192.168.0.2 -- renewal
in 1439 seconds.
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7855]
vpn-connection[0x56338e488110,1a43441b-6b26-4e0c-8343-976afcf790fd,"DataStax
VPN",0]: Started the VPN service, PID 2684
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7950]
vpn-connection[0x56338e488110,1a43441b-6b26-4e0c-8343-976afcf790fd,"DataStax
VPN",0]: Saw the service appear; activating connection
Sep 17 11:43:20 p5520 NetworkManager[1189]: <error> [1505641400.7995]
vpn-connection[0x56338e488110,1a43441b-6b26-4e0c-8343-976afcf790fd,"DataStax
VPN",0]: Failed to request VPN secrets #3: No agents were
available for this request.
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7995]
device (eth0): state change: secondaries -> failed (reason
'secondary-connection-failed') [90 120 54]
Sep 17 11:43:20 p5520 NetworkManager[1189]: <info>  [1505641400.7997]
manager: NetworkManager state is now CONNECTED_LOCAL
Sep 17 11:43:20 p5520 NetworkManager[1189]: <warn>  [1505641400.7999]
device (eth0): Activation: failed for connection 'Połączenie
ethernetowe 1'


Severely broken stuff:
1. Suspend with the dock attached -> ok.
2. Disconnect dock.
3. Try resume -> blank screen, kernel freeze.  

Today I also tried 4.14.rc2, but it looks like it is totally uselesss: network connectivity didn't work AT ALL, not even Wifi, and replugging the dock did not help.