How to use a Firewall to block most Windows processes on a Lan PC

Hi, I'm looking for a way to block all internet access from a specific Windows 10 PC on a home LAN - except for a single application process (a streaming app).

Other than the streaming app, everything else on this PC must be blocked from accessing the internet - including browsing, emails, anti-virus, windows updates, telemetry etc.
I may need the block for half a day or a full day at a time.

Since this PC is on a home Lan, my first thought was to use the Lan Router's features (Netcomm model NF18ACV), but I've looked into that and cannot see a viable way of doing it.
My second idea is to use a Firewall, but I am a novice with firewalls so I'm here to ask the forum for advice.

I looked at Windows 10's Defender Firewall - not particularly user-friendly and seems to be pre-populated with a large number of Inbound and Outbound "ALLOW" rules.
So if I were to use this Firewall, I would want to do the following:
Step 1) Set up the Firewall for a blanket Disallow for all types of comms with the internet by all processes (both operating system and application processes)
Step 2) Then set up a rule that allows only my target app (streaming audio or video) to access the web.

Question: Is this do-able with Windows Defender Firewall? If not, is it do-able with some other third party firewall?

I have installed Tinywall to try it out. After installation, without adjusting anything, Network Discovery and File/Printer Sharing on my pc immediately stopped functioning. I checked Tinywall settings, and sure enough it had check boxes to enable both Network Discovery and File/Printer Sharing to operate through the windows firewall. Though it didn't matter - check box on or off, things stayed broke. Searched the web and spotted some reports of problems from other Windows 10 users of Tinywall. Also found complaints that the developer (one man band) was recently not responsive to bugs and that it worked better for early Windows versions. I could not find an active Tinywall support forum. I really can't comment on the developer's situation but after I uninstalled Tinywall and rolled back to a restore point my Discovery and File sharing perked up working fine again. So for me, with limited tech expertise and limited free time, Tinywall does not seem like a good avenue to invest effort in.

Ok, just spent some time looking into Glasswire, - read some threads in their support forum and there seems to be a few elementary problems you would not expect for paid-for software.

One example: In Win 10, Glasswire's firewall seems to malfunction with portable apps. I quote from a support thread to illustrate the defect where Glasswire's firewall start blocking a portable app previously whitelisted:

Quote: "How to reproduce the problem on any Windows PC:

1. Set Glasswire to “Ask to connect”
2. Download a portable app, e.g. “Kitty”
3. Try to connect to some random IP, it doesn’t matter if that IP really exists
4. Confirm that this app can connect to the internet
5. Restart PC

• At this point Glasswire will block the portable app and won’t ask if it can connect again

1. Delete the portable app from the Glasswire whitelist
2. Confirm (again) that the app can connect to the internet

• The app will work until you restart your PC again

Its really annoying, other firewalls are not causing this problem. I’m not sure why Glasswire behaves like this because the binary name and file hash did not change after a restart. " (end quote)


This issue was raised in FEB 2020 and the Glasswire mod's response is to thank the poster for the info, and promise that support techs will look into the malfunction.

What does this say -- in Feb 2020 Glasswire's firewall cannot handle the whitelisting of something as simple as a portable app.
By all accounts Glasswire excels at network monitoring, but I'm not sure about it's firewalling.

Admin, you can close this thread. I think I should go and hunt for a networking/security specialist resource somewhere since I'm not making inroads into my problem.