Weird incoming connection

Teamviewer just popped up on my machine and said "incoming connection" at the bottom. No one, I repeat, no one should be connecting inbound to this machine but me. The connection was rejected, and I quit Teamviewer after that. I can see the connection attempt in the log, and I can see the ID of the inbound machine and that the connection was denied:

Connection incoming, sessionID = XXXXXXXXXX

2020/03/13 02:24:25.368 5488 6560 S0 AuthenticationBlocker::Allocate: allocate ok for DyngateID YYYYYYYYYY, attempt number 1
2020/03/13 02:24:26.393 5488 6540 S0 UdpConnection is stable: 1
2020/03/13 02:24:26.610 48464 52492 D1!! CAuthenticationSRP_Passive, Step_Receive_VerifyClientSecret: clientSecret!=serverSecret
2020/03/13 02:24:26.610 48464 52492 D1 AuthenticationPasswordLogin_Passive::RunAuthenticationMethod: authentication using fixed password was denied

Is somebody iterating IDs and password stuffing?