reader.ipv6.xsnews.nl less responsive to Teredo IPv6 than to normal/native IPv6

[sander]

Hi, I have a hypothesis:

reader.ipv6.xsnews.nl is less responsive to Teredo/Miredo IPv6 than to 'normal' / nativeIPv6 addresses.

Proof: I have a machine with both Teredo and native IPv6. By specifying the source IPv6 address, I can compare the responses of reader.ipv6.xsnews.nl

First test: ping
ping6 -c4 -I reader.ipv6.xsnews.nl
works for both Teredo and native
This proofs that both IPv6 paths are equal OK

Second test: nntp session
telnet -b reader.ipv6.xsnews.nl nntp
My experience: always response with native IPv6, but no or much less repsonse with Teredo.

This would mean xsnews (or a Teredo server along the way) is throttling nntp traffic over Teredo. Which would be bad news.

I'm thinking about writing a script to periodically test the above.