@Nicholas_Waterton after a restart of openhab with TV switched on I can see this in my log:
2021-11-13 17:04:04.534 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: remoteDeviceAdded: MediaRenderer, http://192.168.200.70:9197/dmr, upnpUDN=e8915dfb_26a1_4f26_9e82_aa3720a00611
2021-11-13 17:04:04.534 [DEBUG] [covery.SamsungTvDiscoveryParticipant] - Retrieved Thing UID for a Samsung TV '[TV] Samsung Q60 Series (55)' model 'QE55Q64TAUXZT' thing with UDN 'e8915dfb_26a1_4f26_9e82_aa3720a00611'
2021-11-13 17:04:04.537 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Check and create missing services
2021-11-13 17:04:04.540 [DEBUG] [covery.SamsungTvDiscoveryParticipant] - Created a DiscoveryResult for device 'QE55Q64TAUXZT' with UDN 'e8915dfb-26a1-4f26-9e82-aa3720a00611' and properties: {hostName=192.168.200.70}
2021-11-13 17:04:04.546 [DEBUG] [nternal.service.MediaRendererService] - 192.168.200.70: Creating a Samsung TV MediaRenderer service
2021-11-13 17:04:04.549 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Started service for: QE55Q64TAUXZT, MediaRenderer (e8915dfb-26a1-4f26-9e82-aa3720a00611)
2021-11-13 17:04:04.550 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, RemoteControlReceiver ()
2021-11-13 17:04:04.553 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Device was online
2021-11-13 17:04:04.655 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: remoteDeviceAdded: dialreceiver, http://192.168.200.70:7678/nservice/, upnpUDN=6ab8611d_47a7_4dde_81c9_8fb03ba1408b
2021-11-13 17:04:04.658 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Check and create missing services
2021-11-13 17:04:04.660 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, MediaRenderer (e8915dfb-26a1-4f26-9e82-aa3720a00611)
2021-11-13 17:04:04.662 [TRACE] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Skipping unknown service: QE55Q64TAUXZT, dialreceiver (6ab8611d-47a7-4dde-81c9-8fb03ba1408b)
2021-11-13 17:04:04.663 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, RemoteControlReceiver ()
2021-11-13 17:04:04.666 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Device was online
2021-11-13 17:04:05.580 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: remoteDeviceAdded: IPControlServer, http://192.168.200.70:9110/ip_control, upnpUDN=9675cba5_4f68_4e4f_ab8b_c16414a2ace6
2021-11-13 17:04:05.582 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Check and create missing services
2021-11-13 17:04:05.585 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, MediaRenderer (e8915dfb-26a1-4f26-9e82-aa3720a00611)
2021-11-13 17:04:05.587 [TRACE] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Skipping unknown service: QE55Q64TAUXZT, IPControlServer (9675cba5-4f68-4e4f-ab8b-c16414a2ace6)
2021-11-13 17:04:05.591 [TRACE] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Skipping unknown service: QE55Q64TAUXZT, dialreceiver (6ab8611d-47a7-4dde-81c9-8fb03ba1408b)
2021-11-13 17:04:05.593 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, RemoteControlReceiver ()
2021-11-13 17:04:05.596 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Device was online
2021-11-13 17:04:07.678 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: remoteDeviceAdded: ScreenMirroring, http://192.168.200.70:9119/screen_sharing, upnpUDN=aa498355_4cea_4ff6_816d_eafb0c89ad57
2021-11-13 17:04:07.679 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Check and create missing services
2021-11-13 17:04:07.681 [TRACE] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Skipping unknown service: QE55Q64TAUXZT, ScreenMirroring (aa498355-4cea-4ff6-816d-eafb0c89ad57)
2021-11-13 17:04:07.682 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, MediaRenderer (e8915dfb-26a1-4f26-9e82-aa3720a00611)
2021-11-13 17:04:07.684 [TRACE] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Skipping unknown service: QE55Q64TAUXZT, IPControlServer (9675cba5-4f68-4e4f-ab8b-c16414a2ace6)
2021-11-13 17:04:07.685 [TRACE] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Skipping unknown service: QE55Q64TAUXZT, dialreceiver (6ab8611d-47a7-4dde-81c9-8fb03ba1408b)
2021-11-13 17:04:07.687 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Service rediscovered, clearing caches: QE55Q64TAUXZT, RemoteControlReceiver ()
2021-11-13 17:04:07.688 [DEBUG] [tv.internal.handler.SamsungTvHandler] - 192.168.200.70: Device was online
As far as I can tell it seems that Upnp is working and finds correctly my TV. But after this I cannot see any other update…