pfSense

Related forum thread here:
https://forum.netgate.com/topic/165744/why-are-the-default-ra-intervals-and-lifetime-values-so-low

In pfSense, these are the default DHCPv6 router advertisement values:

Minimum RA interval: 5
Maximum RA interval: 20
Router lifetime: 60

However, when I look at documentation for other routers, they use much larger values.

Sophos (https://docs.sophos.com/nsg/sophos-firewall/v17.1.4/Help/en-us/webhelp/onlinehelp/index.html#page/onlinehelp/SLAACEdit.html):
Minimum RA interval: 198
Maximum RA interval: 600
Router lifetime: 1800

HPE (https://techhub.hpe.com/eginfolib/networking/docs/switches/WB/16-01/5200-0135_wb_2920_ipv6/content/ch08.html):
Minimum RA interval: 200
Maximum RA interval: 600
Router lifetime: 1800

Microtik (https://wiki.mikrotik.com/wiki/Manual:IPv6/ND):
Minimum RA interval: 200
Maximum RA interval: 600
Router lifetime: 1800

I propose changing the default values to similar numbers the other vendors above are using:
Minimum RA interval: 200
Maximum RA interval: 600
Router lifetime: 1800

By changing those values on my own network, one of my Android 9 devices was able to stay connected to my network for multiple days, where previously it couldn't stay connected for more then 16 minutes (using the default values provided by pfSense). After changing my default values to the proposed values above, I have yet to notice any downsides for the 50+ devices on my network.