instageam multi account with 1 ip

hi.
sorry if my english is too bad
i know some people that make follow action with 21 account at same time and with 1 ip.
someone said me that he can daily build 1000 account with 1 ip and follow with 21 account at same time too. he send to me screen shot.
how is it possible?

Proxy performance varies depending on the type of connection. There's currently 4 types of connections you can use for instagram:

1. IPv6
2. IPv4
3. Residential
4. 4G/LTE

The performance you will get will increase as you go up from 1 to 4.

If you're looking for the best performance, then 4G is what you will need. There are a ton of sellers in the marketplace offering these

It seems quite unrealistic that this guy is able to make 1000 accounts on 1 ip, as well as automating 21 on the same one.
You're either being tricked with fake screenshots or whatever, or they're just using proxies and don't tell you