Can't connect out on IPv6

[Pierre Abbat]

This has been going on for at least a year; I'm not sure how to fix it. My 
DragonFly box (zyxomma) cannot connect on IPv6 on em0 or teredo and 
accumulates teredo addresses. My Linux box (puma) and zyxomma can ping each 
other on the LAN. I originally thought it was a problem with the router, which 
occasionally stops working on IPv6, but it isn't. Here's zyxomma's routing 
table:

Internet:
Destination                      Gateway                          Flags 
default                          192.168.42.1                    UG     
dns1.nextdns.io                  192.168.42.1                    UGH    
dns2.nextdns.io                  192.168.42.1                    UGH    
6to4.pao1.he.net                 192.168.42.1                    UGH    
localhost                        127.0.0.1                       UH     
gotoro.hojmark.net               192.168.42.1                    UGH    
192.168.0.1                      192.168.42.1                    UGH    
192.168.7                        link#2                          U      
192.168.42                       link#1                          U      
192.168.42.1                     00:80:ae:a2:b6:c6               UH     
puma                             b4:2e:99:c2:8d:c9               UH     
teredo.trex.fi                   192.168.42.1                    UGH    
6to4.sjc1.he.net                 192.168.42.1                    UGH    

Internet6:
Destination                      Gateway                          Flags 
default                          localhost                       UG     
default                          teredo                          U      
localhost                        localhost                       UH     
::ffff:0.0.0.0                   localhost                       UG     
2001:0:c38c:c38c:3cbe:b7c5:bcd3:2f7d link#5                      UH     
2001:5b0:2144:59f8::             link#1                          U      
2001:5b0:2144:59f8:222:4dff:fe84:bb1d 00:22:4d:84:bb:1d          UH     
2001:5b0:2144:59f8:1977:5078:1cb7:c2d1 b4:2e:99:c2:8d:c9         UH     
2001:5b0:2144:59f8:a0f0:98d:a9a7:a552 b4:2e:99:c2:8d:c9          UH     
marozi                           teredo                          UH     
fe80::                           localhost                       UG     
fe80::%em0                       link#1                          U      
fe80::222:4dff:fe84:bb1d%em0     00:22:4d:84:bb:1d               UH     
fe80::280:aeff:fea2:b6c6%em0     00:80:ae:a2:b6:c6               UH     
fe80::e333:84e3:760b:57b6%em0    b4:2e:99:c2:8d:c9               UH     
fe80::%em1                       link#2                          U      
fe80::222:4dff:fe84:bb20%em1     00:22:4d:84:bb:20               UH     
fe80::%lo0                       fe80::1%lo0                     U      
fe80::1%lo0                      link#3                          UH     
fe80::%teredo                    fe80::222:4dff:fe84:bb1d%teredo U      
fe80::ffff:ffff:ffff%teredo      link#5                          UH     
fe80::222:4dff:fe84:bb1d%teredo  link#5                          UH     
ff01::                           localhost                       U      
ff02::                           localhost                       UG     
ff02::%em0                       link#1                          U      
ff02::%em1                       link#2                          U      
ff02::%lo0                       localhost                       U      
ff02::%teredo                    fe80::222:4dff:fe84:bb1d%teredo U      

And here's puma's routing table:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    100    0        0 enp9s0
link-local      0.0.0.0         255.255.0.0     U     1000   0        0 enp9s0
192.168.42.0    0.0.0.0         255.255.255.0   U     100    0        0 enp9s0
$ route -6
Kernel IPv6 routing table
Destination                    Next Hop                   Flag Met Ref Use If
ip6-localhost/128              [::]                       U    256 2     0 lo
2001::/32                      [::]                       U    256 2     0 
teredo
2001:5b0:2144:59f8::/64        [::]                       U    100 4     0 
enp9s0
2001:5b0:2144:59f8::/61        _gateway                   UG   100 1     0 
enp9s0
fe80::/64                      [::]                       U    100 1     0 
enp9s0
fe80::/64                      [::]                       U    256 1     0 
teredo
[::]/0                         _gateway                   UG   100 13     0 
enp9s0
[::]/0                         [::]                       U    1029 13     0 
teredo
ip6-localhost/128              [::]                       Un   0   15     0 lo
puma/128                       [::]                       Un   0   15     0 
teredo
puma/128                       [::]                       Un   0   3     0 
enp9s0
puma/128                       [::]                       Un   0   13     0 
enp9s0
puma/128                       [::]                       Un   0   2     0 
teredo
puma/128                       [::]                       Un   0   3     0 
teredo
puma/128                       [::]                       Un   0   16     0 
enp9s0
ip6-mcastprefix/8              [::]                       U    256 13     0 
enp9s0
ip6-mcastprefix/8              [::]                       U    256 1     0 
teredo
[::]/0                         [::]                       !n   -1  1     0 lo

How can I fix this?

Pierre
-- 
gau do li'i co'e kei do