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Pfsense is network perimeter open source firewall software: https://www.pfsense.org/ that is usually installed on a Netgate network perimeter gateway/router appliance; but can be installed on other like compatible devices.
Any questions regarding how to use/configure PfSense in regards to Eset software is beyond the scope of this forum for the most part. Perhaps some Eset Protect EDR installations might be using it and you can post your questions in that forum section. Your best alternative is to open a tech support request with your in-country Eset authorized vendor you purchased your software from.

Please state clearly what you mean, otherwise we can only suggest to contact technical support of your local ESET distributor.

It's always the best to have a router/firewall that is supported by the manufacturer with software updates for sure.
SSDP (Simple Service Discovery Protocol) is a network protocol used in small networks, including home networks, to advertise and discover network services primarily supported by the Universal Plug-and-Play (UPnP) architecture.
I would as first step , go inside the router settings and disable UPnP since it's vulnerable to attacks.

Contacting Microsoft is hard from my experience
But try to go to Advanced Firewall Settings in Windows Firewall or in ESET
And block those :

You can type in Polish but I guess the forum rules indicates that we must communicate in English so others can understand but I can use Google Translate
And as far as I know Linux like Ubuntu when default installed have no open ports unless we open but Kali since is used for Offensive Security where you try to hack as to learn/study/search for vulnerabilities can be different in terms of Ports and also in terms of a system since in Kali you always the root/admin user , where in Ubuntu for example the system will give you a normal user and once you do something that needs an admin , it will ask for the password.
Microsoft on the other hand is different , when Windows is installed there are some ports that are left open and when the PC is left unprotected by a Firewall to the Internet , many bots will jump on it to try and scan it or hack it etc
PFSENSE is better than all of the Home Firewalls you can find in the market in my opinion , it does what it need and more and also if you are looking for something that can be flashed on the router , you can take a look at OpenWRT and maybe you can flash it on your current router

Disable Windows SSDP Discovery service;

As I wrote, most if not all email messages from the archive are recognized as spam by ESET Antispam. If you come across an undetected spam message, please submit it per https://support.eset.com/en/kb141, section Submit spam or spam false positive via email .

I've randomly picked a few messages from the archive and they were detected by ESET antispam as spam. What is the issue then?

I really have no idea what you are referring to here? The fact that Eset alone on VT detects this Nowy folder.rar as malware?
Previous versions of the file have contained ransomware: https://any.run/report/921f2ae14953e2f1d8b88296243fd35381cfacb714d39eb26cbc5e07639c0958/acd02b99-064b-4975-bcdf-556d44b109a0