All of these steps are so painfully obvious that they shouldn't need saying. However, many people seem to be getting themselves banned by being careless so let's list the possible precautions.

Remember - there is NO 100% surefire way to avoid a ban. All people can do is take every precaution possible.

Internet Settings

1. Set a custom DNS - Go to 'change settings' for your connection. The primary DNS should be 104.236.106.125 and the secondary should be 62.210.147.20. This will block connections to the Nintendo servers.

2. Disable 'Connect Automatically' - This forces you to manually connect and thus you can double check the DNS is set up properly. Again, a precaution.

3. Delete all other networks from your Internet Settings - You can never be too careful. Delete any networks you don't need and properly manage the ones you do.

4. Always use Flight Mode when not playing online - Again, this is a precaution to ensure no mistakes. If you need Bluetooth, you can just disable WiFi.

Here we have a 4 layer protection to avoid accidently being online unnecessarily and getting a ban. You can still play online, but the point is that these should all be your DEFAULT settings which you then manually disable when you want to play your (LEGIT) Splatoon 2 online. Remember to re-enable all these settings after you are done playing.

General Usage

1. Set up an extra account purely for Homebrew/piracy usage - This may or may not prevent your main account from getting banned and you losing all your digital purchases. Be sensible, don't use your main account when doing things you're not supposed to. Common sense. And don’t link it to the Nintendo store, keep it a purely offline account.

2. STAY OFFLINE when using CFW, SX etc. - Use flight mode and all the above internet settings when using CFW or SX. Will you really get banned for using CFW? Who knows, But you wanna risk it? Be my guest. Again, precautions.

3. Boot into STOCK firmware when playing online or using eShop - You wanna play Splatoon 2? Great! Just don't do it from within CFW or SX. Cover your back. Turn off your console, boot into stock. Is using legit games online in CFW safe? Maybe. But why risk it? Precautions.

4. Never update backup games or go online with them - This doesn't need explaining. Keep all your misadventures offline.
EDIT - It has been pointed out that people using SX can update their games by rebooting into stock firmware. The game should still appear abeit showing the cart as not inserted. In theory, it should be safe to update from here because no 'fake' cartridge is inserted. That said, it is still a risk. Up to you. Still NEVER update while in SX.

5. If errors occur when using homebrew, clear logs - This can be done by booting Hekate CTCaer, Launch Firmware-> Clear Logs. This prevents homebrew-related errors being sent to Nintendo.

6. Don't install DevMenu - Jury is still out of whether Nintendo can detect this, but having a pirated DevMenu is a pretty big red flag. I'd wait for a homebrew solution to install eShop files.

I wanna play Splatoon 2 online! What do I do?! - Reboot into STOCK firmware, disable flight mode, connect to your network manually and set DNS to automatic. Play your legit Splatoon 2 online. But once you are finished, REMEMBER TO SET THE DNS AGAIN AND ENABLE FLIGHT MODE to avoid any mistakes such as accidentally going online when playing a backup game.

Again - there is no 100% way to avoid a ban and not all of these steps may be necessary. It is all about second guessing Nintendo and taking every precaution possible.

 

[Chipidy]

Not true. Have gone online in my backups of owned carts, played online, no problem. Have done it every day since SX OS 1.1.

Eh, not a risk I want to take . Because the album is a game loader remember

 

[blahblah]

Eh, not a risk I want to take . Because the album is a game loader remember

That app is not dangerous. There has not been a single ban in the scenario I describe. You can choose paranoia or you can determine what Nintendo is checking and meet those checks. I have.

 

[GitGudScrub]

if ur gonna play backups you should just stay offline.
u would get banned eventually anyway

 

[Captain_N]

Wouldn't it be good of the SX OS made a copy of the log files before anything was done and then once it get written with strange activity it will replace the log with the old log. Then Nintendo only sees the old log. ALso shouldnt the SX os stop log file writes?

 

[Giga_Gaia]

There is no precautions you can take that will prevent you from being banned. If you did any modifications to your switch, you will get banned no matter what you do to avoid it. Clearing logs won't work, as someone with no logs is more suspicious. Plus there is the fact that hackers obviously can't delete every logs as they likely don't have access to everything. I bet some logs can only be seen by Nintendo.

Staying offline while being on CFW and only going online on OFW is pointless, the moment you go online, they will know you booted CFW before.

Seriously, you have two choices. Using your Switch for piracy and/or homebrew or using it to play online. You can't have both, you have to choose. Like I said, if you did any modification to your Switch, resign yourself, you will definitely be banned, it's unavoidable. Trying to do anything OP or anyone else mentioned is a waste of time as it won't save you.

Why anyone would care is beyond me anyway. You can still update your games and update your switch firmware if banned. If Nintendo changes that (that's a big if, they likely won't), you will be able to install updates and dlcs manually long before it happens anyway.

 

[whostolemywaffle]

Not true at all. You can't be banned if you have NEVER gone online lmao.

Anyways. What I am doing is simple ( and it's working ). I'm using SX OS - . When I want to play a backup I boot into SX OS and play OFFLINE. When I want to play online, access the Eshop ect, I boot into the OFW ( Official Firmware ). Then I connect to the internet ect.

Before booting back into SX OS I DELETE my internet connection settings.

Also, I actually update my backup games in OFW ( Official Firmware only ). How?

Use at your own risk but it has been working for me since SX OS release.

1: This HAS to be done prior to playing the backup game!
2: Boot into SX OS, go into albums ( game launcher on SX OS ) .Click a game to virtually load it onto the cartridge .
3: TURN OFF console and boot into OFW ( Official Firmware )
4: You will see your backup game in the menu when you boot up! Go to internet settings and connect to the internet .
5: Click the + button on your backup game from the home menu and click software update .
6: It will install the update .
7: Nintendo can't tell if the game is pirated/backup because you never actually loaded the game in the first place , you just "virtually" put it in the slot for a second .
8: After the update DISCONNECT from the internet.
9: Reboot into SX OS .
10: You are welcome

Thank you for the tips its very appreciated !