Could someone please help me and tell me what does "DevFee : Stop mining and disconnect" means ? And if there is anyway to fix it in case I'm doing something wrong.
You pay Claymore (The developer of this miner) either 1 % or 2 % of your mining time, which depends on if you are dual or solo mining.
For that to happen the miner connects to the server the dev (claymore) has defined and mines for a certain time there. Then it switches back to your own pool.
It is normal for this miner and has to be considered when choosing your miner.