[BC] Who and why??

I have a DPC3825 and today I noticed 192.168.0.10 listening on my router. I have bridge mode and never see 192.168.0.xyz. I could even access my router user page which is always impossible in bride mode. Why would this show up?? Also when I tried to log in, nothing happened. It took my password but just stayed on the same page, the status button does nothing also.