Abyss Dungeon Disconnection

Region: NA EAST
Server: Galatur
Name: Binhvan
Dungeon: Tranquil Karkosa
Hello, I was doing this dungeon with my friend pillowpants and were trying to progress through the abyss dungeons when I started to disconnect on the last boss yesterday. I saw my ping spiking up to 700 ms and tried to keep reconnecting and kill the boss but the game would not allow me to. I did not get the reward nor the completion. They managed to kill the boss but now I am locked out and don’t know what to do. Can you help resolve this problem?