My minecraft server being ddosed? Or is it something wrong with my Router?

I have a popular minecraft server, Portforwarded so others can play. Now recently me and my boyfriend have been wondering why it keeps getting reset and I have to reportforward every other day, or every day. Well An admin I have just banned admit to saying he's been ddosing my game. So is this a cause of being ddosed or is my router having problems?

DDOS would never change your port forwarding. Possibilities are that the router is resetting somehow (faulty router or router power supply), or the MC server is changing local LAN IP address.