Network oddity ?

You really want a simple switch which will connect the ethernet devices with minimal overhead. There may well be some built-in filtering in the BT hub which stays in operation even with the firewall off, and there is almost certainly some unnecesary routing overhead. An example for little money:

Somewhere in a box somewhere I have one.

That said, I do use the wireless bit of the BT Hub too ...

You only need one lead (from the switch) to the hub to use it as a wireless access point.

That's a possibility, although I would have said unlikely. However we've already established it's not behaving normally, so perhaps the improbable is now likely. It would be worth a try.

For the record that's a 10/100Mbit switch. Nothing wrong with that, but at this point in time I'd spend a fiver more and buy a gigabit switch.

Theo

Good point! I didn't know they still made them.

Just thought I'd update this ....

a bit more messing around confirmed 100% whatever was happening was happening in the BT Hub3 Router. I tested a whole gaggle of phones and tablets via it's wireless connection and none of them could see the DLNA server.

HOWEVER - they call all see the same machines SMB shares.

Because lifes too short, I swapped the router for a really old 2Wire one I had, and it's working as intended. TV can immediately see the DLNA server.

I did note that restarting the DLNA program did something, as after that it was available via the router. But I have no intention of doing that every evening as a fix.

Sounds like something relying on uPNP?

DLNA is a sunset of UPNP.In order to propagate it across a gateway you need it enables on the router.

The DLNA client expects to receive an 'I am here' message via the PNP mechanism (I think). But that requires using a multicast protocol and that is something that routers may decide not to propagate. I am not

I think in most routers there is a tick box 'saying 'allow UPNP' and once ticked the stuff should 'just work'

Failure to enable UPNP fits the described symptoms exactly - perfectly good network access to everything except the DLNA server.

Except the box was ticked.

And it wasn't that DLNA *never* worked. But that it had to wait for "something" to happen before the TV (or any other device) could see the server.

I did briefly think that accessing the internet (e.g loading iPlayer) was "clearing" the problem. But a few nights waiting and waiting and waiting suggested it wasn't that simple.

But as I say: swap Hub3 router for 2Wire Router and problem disappeared.

As TNP says DLNA is a subset of uPNP. Which is (well was) enabled on the Hub3 router. With the additional twiddle that I messed around with disabling "Enhanced uPNP security" to no effect.