UPDATE: You need to block more than one server now, refer to this post for list of update server you need to block in addition to the one in the tutorial.
Guide to blocking http://sun.hac.lp1.d4c.nintendo.net:443 with Fiddler.
This allows you to only block system firmware updates. Game updates, eshop and friends will all still work. You can also block other URLs as they are discovered. This gives you greater control than just using someone else's DNS and then waiting for them to update their block list in the future or even spying on you.
1) Download Fiddler.
https://www.telerik.com/docs/default-source/fiddler/fiddlersetup.exe?sfvrsn=4
2) Install Fiddler then execute the application.
NOTE: If you firewall warning pops up at anytime during this tutorial please allow Fiddler full access.
3) Open the menu "Tools/Telerik Fiddler Options".
Select the option "Allow remote computers to connect".
Remove the option "Act as system proxy on startup".
Click "OK".
Guide to blocking http://sun.hac.lp1.d4c.nintendo.net:443 with Fiddler.
This allows you to only block system firmware updates. Game updates, eshop and friends will all still work. You can also block other URLs as they are discovered. This gives you greater control than just using someone else's DNS and then waiting for them to update their block list in the future or even spying on you.
1) Download Fiddler.
https://www.telerik.com/docs/default-source/fiddler/fiddlersetup.exe?sfvrsn=4
2) Install Fiddler then execute the application.
NOTE: If you firewall warning pops up at anytime during this tutorial please allow Fiddler full access.
3) Open the menu "Tools/Telerik Fiddler Options".
Select the option "Allow remote computers to connect".
Remove the option "Act as system proxy on startup".
Click "OK".
4) Back on the main screen select "AutoResponder" tab.
Select the option "Enable Rules".
Select the option "Unmatched requests passthrough".
5) Click "Add Rule".
Copy and Paste this into the rule editor: EXACT:http://sun.hac.lp1.d4c.nintendo.net:443
Select "*drop" from the list in the bottom box.
Click "Save".
5) Make sure your new rule looks like this.
CLOSE and RESTART Fiddler.
6) Double check your firewall is open to Fiddler.
Search for "Windows Firewall" in your start menu or find it though control panel.
Select "Allow an app or feature through Windows Firewall".
Scroll down the list and make sure Fiddler is allowed in "Private/Domain" or "Public" if you are on a public network.
7) TURN OFF AUTO-UPDATE on your Switch!
Set up a proxy on your Switch.
Server = IP Address of the computer running Fiddler
Port = 8888
Click Save.
Restart your Switch. Note: Hold power button down for 5 seconds then choose restart from power options
8) Now connect your Switch to your network.
You should see Fiddler blocking the update server in real time.
If you do not see the red block icon and instead see a grey padlock, then something went wrong. Double check the spelling of the URL.
If your Switch cannot even connect to the network, there may be a firewall issue with the computer running Fiddler.
9) Fiddler must be running from now on for your Switch to be able to access the internet. If it is not running, your Switch will not be able to access the internet.
10) Profit.
Check here for a list of URLs and their purpose.
Last edited by Mr. Wizard,