Yes. IMO unfortunately regarding IPv6, since it breaks the end-to-end connectivity, which should be one of the points of having IPv6. Anyway, this can be fixed by a simple firewall rule like this:
config rule
option name 'IPv6 in'
option family 'ipv6'
option src 'wan'
option dest '*'
option target 'ACCEPT'
If you feel this is too much open, you can restrict the rule just for dynamic ports so most PtP applications could work by adding these two lines:
option proto 'tcpudp'
option dest_port '49192-65535'