If you have a dynamic IP, it could be that the previous user of that IP was running an TOR exit/VPN.
If you have a static IP, I strongly recommend researching whether the router you are using has any known security problems. Lately unsecured routers have been abused as a (poor) black hat's proxy a lot.
Source: I run a filesharing service and lately we have seen a lot of abuse from IPs who after an nmap reveal themselves as routers with known security problems like publicly known (default) service control panel passwords.
If you have a static IP, I strongly recommend researching whether the router you are using has any known security problems. Lately unsecured routers have been abused as a (poor) black hat's proxy a lot.
Source: I run a filesharing service and lately we have seen a lot of abuse from IPs who after an nmap reveal themselves as routers with known security problems like publicly known (default) service control panel passwords.