they seem to consider that IPV6 should work 
https://github.com/matrix-org/synapse/pull/1696
edit: you’re right, it’s a bug in Twisted (the networking engine) https://twistedmatrix.com/trac/ticket/8877
they seem to consider that IPV6 should work https://github.com/matrix-org/synapse/pull/1696
edit: you’re right, it’s a bug in Twisted (the networking engine) https://twistedmatrix.com/trac/ticket/8877