If you are using Symantec, I know which program you have as I have the
same one and it is pretty good at catching rogue systems.
As to someone
finding out your router password, you need to change it and also,
depending on the brand that you have, at least on Linksys, there is a
tab in which you input the MAC addresses of the systems that are allowed
on your network. When you input all of your systems, smartphones, tablets, laptops, ensure that you
click on the button that states “Allow Only These MAC Addresses”. Now,
if someone is able to access the password to the network, which MUST be different than
the admin password, then you will know and it makes it harder for them
to use your network.
Also, change the admin to another name and not the