I am using 4G network with 5 accounts on 1 device and it works great, no problems, I will stick with 4G because I just think it is safer than VPN. I tried VPN for 4 days with 1 account and I didn't have any problem neither.
What I am doing is using the same IP for each 2 accounts and when I am going to log into the third one, I turn on and off the airplane mode so I get a new IP from my network provider.
The old accounts that were IP shadowbanned are still shadowbanned after two weeks, so it is not a normal shadowban. Let's see how long it takes.
In the future I will only be using 4G network, I recommend to everyone that manually manage more than 5 accounts to use 4G network, it may be a bit expensive depending on your country but it is better than getting banned your network of accounts.