Poor IPv6 experience with Ubiquiti

[YoRyan]

Since you guys are IPv6 nerds, I think you'd appreciate my rant.

I decided to overhaul the parents' home network after their ancient TP-Link equipment kicked the bucket. I went with Linksys Velop for wireless access points, since they are affordable, support 802.11kvr, and are often in stock at your local Walmart. For the router itself, I purchased an Ubiquiti EdgeRouter-X, since the Internet hypes up anything Ubiquiti makes as "enterprise grade for consumer cost." The Velops have been performing well and I am consistently impressed with their capabilities. The "prosumer" EdgeRouter, on the other hand, has turned out to be a total lemon.

Out of the box, IPv6 didn't work at all, since Ubiquiti had broken DHCPv6 for certain ISP's (Charter-Spectrum in Central California among them) in one of their firmware updates. They soon fixed it with another update, but then IPv6 would mysteriously stop routing packets after a day or two of uptime. In this state, the EdgeRouter would still advertise a prefix and send outbound packets, but it would not receive any responses from the cable provider. My parents noticed when their apps and browsers would spend several seconds trying unsuccessfully connect over IPv6 before finally falling back to IPv4.

By this time, I was fed up with Ubiquiti, so I never did troubleshoot this condition in detail. Instead, I flashed the EdgeRouter with OpenWrt. That setup lasted about 4 days before I got reports of complete network failure. After I googled a bunch of bug reports, I think what was happening was that OpenWrt's driver for this particular Mediatek chipset was somehow soft-locking the Ethernet controller.

So I bought a Raspberry Pi 4 and a managed switch, set up OpenWrt in a router-on-stick configuration, and sold the ER-X on eBay. Now IPv6 is working much more consistently. Unfortunately, Spectrum seems to have a habit of invalidating the IPv6 prefix after a few days of uptime, which causes a few hours of IPv6 downtime, but at least OpenWrt gives me the tools to investigate and implement a workaround.

Avoid Ubiquiti, folks.

[K6USY]

I personally use PFSense, it has a lot of IPv6 settings that can work with almost any setup. I was even able to get dual stack working with AT&T fiber directly, completely bypassing the router they provided.

Central CA you say... I'm up in Fresno and work for the public library system so you may be in my service area.

[YoRyan]

I'm an OpenWrt partisan for its software ecosystem and web interface. When you have well-supported hardware, it works beautifully; otherwise, reliability can be kind of sketchy. But that's really Mediatek's fault for not mainlining their chipset drivers, and of course Ubiquiti is under no obligation to support OpenWrt.

They are obligated, however, to support IPv6.

You're with the San Joaquin Valley Library System, right? I'm from Bakersfield.

[K6USY]

You're with the San Joaquin Valley Library System, right? I'm from Bakersfield.

Yep, I do all the networking for SJVLS including the libraries in Kern County.  We currently have 89 of our locations dual stacked. 

[cvmiller]

I too was surprised at the poor IPv6 support (using the Web GUI) for this router. You _can_ put OpenWrt on it, and then the IPv6 support (including DHCPv6-PD for downstream routers) works great.

I wrote this up in a blog:

http://ipv6hawaii.org/

[YoRyan]

When I ran OpenWrt 19.07.3 on my ER-X, the router would become unresponsive after several days of uptime. Never did nail down the issue. I think it's related to this ongoing issue on MT7621 systems.