In the meantime, I've contacted NJoy Digital about the issue. In summary, this is what we discussed:
1. The Njoy Player works fine in the local setup as well as in my 'production' network setup including a router or switch (I've tried both). On a side note, fixing the deinterlacing issue was just a matter of enabling 'optimize for quality' in the player.
2. Since the streaming problem also occurs on a local laptop DVBLink installation with a direct (no router) ethernet connection, the LAN setup is assumed not to be the issue.
3. Since one would expect UDP streaming to at least work without dropouts etc. in the direct connection setup (including using realtime prio for the DVBLink server process), NJoy assume that there is something wrong with the UDP streaming implementation (from N7 to server) in DVBLink.
4. NJoy state that they had already contacted DVBLogic about the streaming issue (after I had reported it to them) and that DVBLogic had indicated a new version of DVBLink for AnySee N7 would be available in 4.5, although the exact timing is currently unclear.
5. NJoy claim that the N7 can and should stream perfectly using UDP as well as TCP.
6. NJoy informed me that they have a strict agreement with DVBLogic that issues, such as the one I raised here, be directed to and addressed via your forum, because this would ensure that DVBLogic get the chance to address these issues (assuming they are software-related).
With regard to item 4, I know that 4.5 is currently in beta, but haven't read anything about N7 (UDP or TCP) streaming. Can you comment on this?
For the time being I can live with the issue by using NJoy's player for cable channels, but obviously I'd highly appreciate some reasonable timing indication for a solution, other than 'not in the short or mid term' which sounds like I (and other N7 owners) would have to wait at least a year before getting support.
By the way, can you confirm for yourselves that there is a streaming issue using an N7 in a setup of your own?