I have been having this issue for a couple of months now where, if I suspend my notebook, while it is attached to the router via Ethernet, the entire network basically stops working (wired and wireless).
The notebook is attached to the router either directly via an Ethernet cable, or through a docking station, and in both cases the network stops working. Whipping out my trusty wireshark on another computer, I can see a lot of ARP requests that seem to go unanswered since the same hosts issue queries over and over again. Most of the queries are going from/to the configured gateway IP (192.168.0.1, a.k.a. the router) which is not surprising, but could be an indication. The router is an AVM Fritzbox 4040. The queries originating from the router are looking for the former notebook IP, while the queries to find the router are from a Synology NAS attached directly to the router (and the return address is 169.254.x.x which seems wrong to me).
Unplugging or resuming the notebook resolves this issue.
It's not a big problem, given that the temporary fix is rather simple, but I'd like to understand what is going on.