About 2 years ago I bought a used computer from ebay.... as seeing it fresh and assumed the previous owner have reformatted so did not reformat myself. About 3,4 years ago bought a used Router from ebay. Straight up connect it to the internet right away. Heard that if buying a used router and did not reset and check if any ports are open by the previous owner.... may be secuirty risk. How do I check if my router are safe? and how to reset router? it doe snot come with manual. It is a Buffalo router... white color..... full metal jacket.... small size.