IPv6 anycast (2a07:a8c0::, 2a07:a8c1::) unreachable from Verizon FiOS (EWR region)

Hey,

IPv6 connectivity to NextDNS anycast addresses (2a07:a8c0:: and 2a07:a8c1::) has been intermittently failing for several weeks for me. When it fails, packets black-hole inside upstream networks (Vultr and Telia) before reaching NextDNS. However...IPv4 anycast works perfectly every time! Both 45.90.28.0 (vultr-ewr) and 45.90.30.0 (anexia-ewr) respond with ~7ms latency. I'm on Verizon FiOS in the NYC/Newark area. The issue affects any and every machine on my network which is quite frustrating. It seems to be localized as I have servers outside the area in Europe that do not have this issue..

Diagnostic output:

```
Testing IPv6 connectivity
  available: true
Fetching https://test.nextdns.io
Fetch error: Get "https://test.nextdns.io": dial tcp: lookup test.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:36235->127.0.0.53:53: i/o timeout
Fetching PoP name for ultra low latency primary IPv4 (ipv4.dns1.nextdns.io)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp: lookup ipv4.dns1.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:34552->127.0.0.53:53: i/o timeout
Fetching PoP name for ultra low latency secondary IPv4 (ipv4.dns2.nextdns.io)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp: lookup ipv4.dns2.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:43384->127.0.0.53:53: i/o timeout
Fetching PoP name for anycast primary IPv4 (45.90.28.0)
  vultr-ewr: 6.331ms
Fetching PoP name for anycast secondary IPv4 (45.90.30.0)
  anexia-ewr: 7.877ms
Fetching PoP name for ultra low latency primary IPv6 (ipv6.dns1.nextdns.io)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp: lookup ipv6.dns1.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:36200->127.0.0.53:53: i/o timeout
Fetching PoP name for ultra low latency secondary IPv6 (ipv6.dns2.nextdns.io)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp: lookup ipv6.dns2.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:57509->127.0.0.53:53: i/o timeout
Fetching PoP name for anycast primary IPv6 (2a07:a8c0::)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp [2a07:a8c0::]:443: connect: connection timed out
Fetching PoP name for anycast secondary IPv6 (2a07:a8c1::)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp [2a07:a8c1::]:443: connect: connection timed out
Pinging PoPs
error: Get "https://router.nextdns.io/?limit=10&stack=dual": dial tcp: lookup router.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:48379->127.0.0.53:53: i/o timeout
Traceroute error: lookup ipv4.dns1.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:48517->127.0.0.53:53: i/o timeout
Traceroute error: lookup ipv4.dns2.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:38666->127.0.0.53:53: i/o timeout
Traceroute for anycast primary IPv4 (45.90.28.0)
    1    192.168.1.1    0ms   0ms   0ms
    2    173.68.66.1   13ms   1ms   3ms
    3 100.41.198.158    6ms   3ms   4ms
    4                   *     *     *
    5 208.214.138.94    *     *     6ms
    6   4.69.208.178    *     4ms   7ms
    7    65.59.14.18    5ms   7ms   7ms
    8                   *     *     *
    9                   *     *     *
   10                   *     *     *
   11     45.90.28.0    8ms   7ms   8ms
Traceroute for anycast secondary IPv4 (45.90.30.0)
    1    192.168.1.1    0ms   0ms   0ms
    2    173.68.66.1    3ms   4ms   3ms
    3 100.41.198.158    8ms   7ms   4ms
    4                   *     *     *
    5                   *     *     *
    6 62.115.135.160    5ms   *     *
    7  62.115.112.69    *     *     7ms
    8  80.239.197.18    4ms   8ms   7ms
    9     45.90.30.0    4ms   8ms   7ms
Traceroute error: lookup ipv6.dns1.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:38188->127.0.0.53:53: i/o timeout
Traceroute error: lookup ipv6.dns2.nextdns.io on 127.0.0.53:53: read udp 127.0.0.1:51748->127.0.0.53:53: i/o timeout
Traceroute for anycast primary IPv6 (2a07:a8c0::)
    1 2600:4040:975a:2900::1    0ms   0ms   0ms
    2 2600:4040:9730::1    7ms   5ms   2ms
    3 2600:4000:1:132:8000::8    *     *     4ms
    4   2600:802::20    4ms   4ms   4ms
    5 2600:803:d0f::14a    *     *     4ms
    6 2001:1900::3:19b    3ms   4ms   3ms
    7 2001:1900:2100::64fe    6ms   7ms   8ms
    8 2001:19f0:fc00::a40:41a    8ms   7ms   8ms
    9 2001:19f0:fc00::a40:7e2   10ms  12ms  10ms
   10 2001:19f0:fc00::a40:886    5ms   7ms   8ms
   11                   *     *     *
   12                   *     *     *
   13                   *     *     *
   14                   *     *     *
   15                   *     *     *
   16                   *     *     *
   17                   *     *     *
   18                   *     *     *
   19                   *     *     *
   20                   *     *     *
Traceroute for anycast secondary IPv6 (2a07:a8c1::)
    1 2600:4040:975a:2900::1    0ms   0ms   0ms
    2 2600:4040:9730::1    3ms   3ms   4ms
    3 2600:4000:1:132:8000::8    *     7ms   *
    4   2600:802::1b    *     4ms   3ms
    5 2001:2035:0:bc3::1  303ms   *     *
    6                   *     *     *
    7 2001:2034:0:249::1    6ms   3ms   4ms
    8 2001:2035:0:c44::2    3ms   4ms   7ms
    9                   *     *     *
   10                   *     *     *
   11                   *     *     *
   12                   *     *     *
   13                   *     *     *
   14                   *     *     *
   15                   *     *     *
   16                   *     *     *
   17                   *     *     *
   18                   *     *     *
   19                   *     *     *
   20                   *     *     *
```