I have a smoothly functioning C4000 A20 for nearly 2 months now.

In exploring the many advanced features, I saw that my IPv6 option is NOT turned on.

I've asked a few experts around and the consensus is as follows:

1 - first and foremost, your ISP must support it.  (I'm in the process of finding out).

2 - the client side (in my case, mostly Windows 10 PCs/laptops, Apple and Android smartphones) must support IPv6.  Win10 yes.  Apple iOS and Android, don't know.

3 - websites that I (and most ordinary internet users) access are still predominantly IPv4 only. 

4 - there are growing number of IPv4 and IPv6 websites -- i.e., can support both.

5 - there are still very few "IPv6 only".

It is when the client side (Win10 PCs in my case) needs to access a server that supports only IPv6 (#5) that I will need to turn on this IPv6 feature on my router.

Otherwise keep IPv6 turned OFF on my WiFi router.

Do the above make sense?  As an ordinary non-expert user of the Internet, I have no idea when a website I wish to access if "IPv6 only".  I;ve used a few "test your IPv6" sites such as "test-ipv6.com" , "testmyipv6.com" ... got some info back half of which is not totally understandable to me.

Do I need to "worry" about turning on IPv6?  If I do, will there be overhead to my router's processor?

Would be grateful for any general advice, tips and guidance.

Thanking you in advance.