IPV6 preferred lifetime does not update

Hello

I have a NetGear Nighthawk AX12 (RAX200).

I have enabled IPV6 and it is set to autoconfig. 

The IPV6 address on my computer is set when I enable IPV6 in the router. But after a while I don't have IPV6 connectivity anymore.

I did some digging and found out that the IPV6 address on my computer is set by the ICMPv6 type 134 packets (router advertisements) sent out by the router.

These packets contain a preferred and valid lifetime that tell my computer how long the IPV6 address should be used.

This lifetime is set to ~ "71558" when I enable IPV6 in the router. In the following ICMPV6 type 134 packets this value counts down to 0 and is never augmented anymore... because of this I loose my IPV6 connectivity. 

I verified this with Wireshark and "Netsh interface ipv6 show addresses" in powershell on my computer. 

Is there a setting in the router that I am missing? Or is this a bug? What should I do to correct this? (yes I can use the DHCP server setting instead of auto config for IPv6, but Android does not support this)

Thanks