Comcast’s router acts as a gateway but has a hardware, built-in firewall.. The router which I use has a built-in, hardware firewall. In addition, I have software firewalls and anti-virus programs on the computers. I haven’t had any issues in years and years. Nothing, and I mean NOTHING gets into these computers unless I say so!
My offhand guess would be that you or someone else clicked on a bad site and/OR answered a suspicious email.
i was with comcast for years.. they kept raising my rates and i got fed up.. i watch maybe 3 channels for 180 dollars... i messed with them for the last time.. went with att since they laid cable up our street.. dug my yard and into watering system.. they were no better.. 2 yrs.. and went with roku.. dont like it but cheaper and lots of channels..
my router is my own and not pleased with it but trying to make it do what its supposed to.