@Juhana 

Hi. Thanks for your reply. 

It was clear and quite understandable article, what many articles are not. I'm wondering if it's still accurate information, because it was published in November 15, 2019.

There was this sentence: Earlier versions of Windows did not have RDNSS support while Android and Chrome OS still do not have DHCPv6 client support.

On my Honor 9 running Android 9, there is both IPv4 and IPv6 address, under network information section. So router's default setting SLAAC+Staless DHCP probably work's fine. The AX10 Router setting: DHCPv6, which is probably maybe meaning same than DHCPv6 Client (M & O flag), is not supported by Android? Is that still true?

 

In my home network is router (and switches) hosting at least 15 client's; Android phone's and tablet's, Chromebook, Chromecast dongle, iPhone,             Win 10 computers, Win 7 computer, Ubuntu and Mint computers,televisions, printers, NAS device, TP-Link RE505X ertender, Trendnet AP broadcasting separate 2,4GHz WLAN to control Roomba.

The reason that find and got curious about IPv6 LAN-settings is explained below.
I have been poking router and extender settings because connection problems. At first extender started to shut down right after it was started, and second problem was that router lost it's connection to internet every 2h or something like that. I did automatic problem solver task from my ISP's site, and it said that  there is poor connection. ISP send maintenance guys to change my fiber optic terminal to new one. They changed it although they didn't find that there was no problem with connection with optic terminal and ISP server. Changing terminal didn't help, but at same time I ended to upgrade from 250Mbit/s connection  to 1000Mbit/s connection, so that's good. I looked every possible setting in the router and did some changes. Network is now have been up about 24h. I don't know what setting fixed that, it was maybe to set router time to manual, because logs have some boot-up dialog that indicated that at  beginning half of booting, time was not correct, and router had to get connected to internet before time was set correctly. I don't know is this way automatic time settings usually works or not. I also enabled TP-Link Dynamic DNS, set an OpenDNS account and changed routers default DNS IP's to OpenDNS addresses. Last I disabled extender DHCP. (I think so the main router handles all DHCP tasks, right?)

Yes I tough so too, but doesn't router have any backup battery like computers, that keeps time on running or in memory? I think I will wait for some time, and when I really must to reboot router, I check if time is correct. Thanks for extender DHPC settings confirmation.