@Tim91 I think you may be able to tell by the tone of most of the responses to your questions, that you may not get the help you seek here.
Network security is a very complex subject and there are no absolute, 100% foolproof solutions. Generally, the stronger the protection, the harder it is to configure and maintain.
A general rule is that if you think you have an infected device,
disconnect it immediately from your network and don't connect it to the internet. If you need to do a malware scan or install an antivirus tool, load it onto a flash drive on a known-good computer and sneaker-net it over to the suspect machine. But in no case should you connect the suspect device to your network until you know it is clean.
If you don't have the skills to do this, the best thing is to take it to a service professional who can properly diagnose and clean the machine. But be advised a lot of malware these days is pretty persistent and can burrow into the root partition of your hard drive. In that case, the best course of action is to replace the drive and do a clean install of the operating system, then the applications. Before you install anything from a backup, be sure to virus scan it.
As far as a router being infected by malware, that is less likely. In many cases a factory default result, as
@Christos suggested will take care of the problem.
Finally, as
@Centrifuge pointed out, understanding the source of the malware can help you decide on the kind of protection you need. But good, robust, use-friendly firewalls at the price average consumers are willing to pay are very hard to find. And any decent solution will likely be subscription-based, which, again, most consumers don't want to pay for.