TLDR: I provide network rentals and leases among other related services. I started providing IPv6 by default in 2019 ish and recently started noticing spotty connectivity on mobile devices only. Was wondering if anyone else has ran into this.
Following recent chatter about IPv6 I thought I would ask here to see if anyone has experienced spotty IPv6 connectivity on Android devices or iOS devices recently? I started providing IPv6 connectivity in all of my networks back in 2019 ish. Recently I moved a bunch of internal stuff to IPv6 only and quickly started to understand that IPv6 connectivity for mobile devices on my networks was not completely reliable. Apparently randomly I will find that my Android or iOS devices do not have IPv6 connectivity and upon checking will find that they do not have any IPv6 addresses. I've tested Android devices hard wired to the network and this is also impacted. Increasing advertisement lifetimes helped significantly however the problem is still occurring occasionally. The issue is also replicated with iOS devices. I've tried enabling IGMP snooping and Ubiquitis multicast enhancement which didnt appear to make any difference. I've not had any customer reports of issues; though this is expected since they are not reliant upon IPv6 working and failover mechanisms are generally robust at present. I believe that the issue may be occurring if a device has poor signal when it initially connects to the network. This is ultimately unavoidable because for example your device may associate with the network in your house as you approach from the road. Most of my networks are designed to have -70dbm or better signal in all areas with 50% overlap. Typically I disable lower PHY rates to ensure devices roam promptly and do not cling onto the signal when they have poor coverage (ie when leaving the coverage area). I believe that this may have something to do with devices becoming 'deaf' to broadcast traffic some time after they connect to the network. I monitor all of my networks including IPv6 using firebricks so the underlying connectivity is known to be good. Additionally various servers, Windows desktops, linux laptops, printers and other devices are connected both wirelessly and hard wired and I've not noticed any problems. Some of these devices are actively monitored with no significant issues detected. At a high level my networks consist of a PC based router, running linux, IPTables ISC Named, ISC DHCPD, RADVD and Wide DHCPv6c. Most of my networks run on the BT Business network and get a /56 static delegation via DHCPv6. I then carve this up into /64s with one assigned per VLAN. Network equipment wise most of my networks use Netgear managed switches and UniFi access points. Most stock is currently WiFi 5 or WiFi 6 era. Advertisement valid lifetime is set to 2592000 with preferred life time set to 604800. Any thoughts or anecdotal experience would be valued here. For what its worth my default check for whether I have working v6 connectivity is to load up www.loopsofzen.uk or refresh one of my internal v6 only pages. Alan
