How permanently disable ipv6?

Hello,
please anybody do know how permanently disable ipv6?

This is working:

Code:

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sysctl -w net.ipv6.conf.all.disable_ipv6=1
sysctl -w net.ipv6.conf.default.disable_ipv6=1

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but after off/on wifi is ipv6 again running.

I have Purity ROM 5.1.1_r13 - LVY48E

Thanks