DOS

I got the following security log from my router:

TCP Packet - Source:87.1.133.229,1904 Destination:87.11.170.78,4662 - [DOS]
TCP Packet - Source:87.29.108.179,4208 Destination:87.11.170.78,4662 - [DOS]
TCP Packet - Source:87.2.183.167,4262 Destination:87.11.170.78,4662 - [DOS]
TCP Packet - Source:151.49.226.83,2638 Destination:87.11.170.78,4662 - [DOS]
TCP Packet - Source:82.58.49.228,4724 Destination:87.11.170.78,4662 - [DOS]
TCP Packet - Source:211.191.122.99,2345 Destination:87.11.170.78,4662 -
[DOS]
TCP Packet - Source:85.60.13.37,14992 Destination:87.11.170.78,4662 - [DOS]
TCP Packet - Source:151.49.194.135,1248 Destination:87.11.170.78,4662 -
[DOS]
TCP Packet - Source:82.51.35.201,1917 Destination:87.11.170.78,4662 - [DOS]

which I understand being a Denial of Service attack towards port 4662, which
I left open on the router as it is serving p2p applications.

The attack seemed to have no consequences (or I didn't notice) but I was
wondering if there is anything I can do to improve security.

Thank for any suggestion
S