A lot of connections to port 6881 - some new attacks or what?
Solution 1:
Use Wireshark (or similar) and have a look at what the traffic is, rather than just looking at what port it's for. That may give you a clue. Port 6881 is most likely bittorrent traffic but may also be the result of malware. Check your internal traffic as well, looking for signs of bittorrent traffic.
Solution 2:
wargaming.net is using port 6881 for p2p game files. Most likely someone on the network is playing games.