Interesting journey, but I'm not sure any of this will help you...!
1. Installed Video Station. Plugged in USB tuner. Scanned for channels. Waited a lifetime (man, that's slow)
>> Detected channels, confirmed that I can record. So the USB tuner is working fine with the Synology
2. Shut down Video Station, started tvheadend
>> No tuners visible
3. Rebooted
>> Still can't see the tuner
4. Checked dmesg - permission problem?
Nov 26 14:11:57 tvheadend[7842]: dvb: Unable to open /dev/dvb/adapter0/frontend0 -- Permission denied
Nov 26 14:11:57 tvheadend[7842]: dvb: Unable to open /dev/dvb/adapter1/frontend0 -- Permission denied
Nov 26 14:11:57 tvheadend[7842]: dvb: Unable to open /dev/dvb/adapter2/frontend0 -- Permission denied
Ran
find /dev/dvb -type c -exec chmod 666 {} \;
to force the permissions (actually, I tried 777 beforehand, but with no difference); restarted tvheadend
>> nothing
5. Uninstalled Video Station to see if it was clashing; restarted tvheadend
>> nothing
6. Rebooted
>> nothing
7. Reinstalled Video Stationand started it, then restarted tvheadend
>> success, I can now see the tuner (I think you need Video Station running to load the tuner firmware?)
>> I also note that the permissions are now 777, which may be related
8. Manually added muxes
>> All identified and named correctly, all scanned and services identified
>> Network was correctly identified as Gloucestershire (not blank as you have); mux IDs were identified for all but the HD/DVB-T2 mux (it's a DVB-T stick, so that's expected).
A thought here - all I set was the base frequency and the bandwidth (8MHz) for each mux; everything else was set to Auto. I notice you've set QAM64 and 8k-mode. Have you tried adding them as auto?
9. Map DVB services to channels
>> 117 service turned into 50+ channels (I wouldn't expect to get them all, although this may be lower than intended).
----
Comparing my files to yours... in @/usr/local/tvheadend/var/dvbtransports@:
_dev_dvb_adapter0_DiBcom_7000PC474200000
_dev_dvb_adapter0_DiBcom_7000PC498000000
_dev_dvb_adapter0_DiBcom_7000PC506000000
_dev_dvb_adapter0_DiBcom_7000PC522000000
_dev_dvb_adapter0_DiBcom_7000PC530000000
... so one per active mux. Changing into the first of these:
_dev_dvb_adapter0_DiBcom_7000PC474200000_3280
_dev_dvb_adapter0_DiBcom_7000PC474200000_32c0
_dev_dvb_adapter0_DiBcom_7000PC474200000_32e0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3340
_dev_dvb_adapter0_DiBcom_7000PC474200000_37c0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3824
_dev_dvb_adapter0_DiBcom_7000PC474200000_38a2
_dev_dvb_adapter0_DiBcom_7000PC474200000_38c4
_dev_dvb_adapter0_DiBcom_7000PC474200000_3960
_dev_dvb_adapter0_DiBcom_7000PC474200000_3980
_dev_dvb_adapter0_DiBcom_7000PC474200000_39a0
_dev_dvb_adapter0_DiBcom_7000PC474200000_39c0
_dev_dvb_adapter0_DiBcom_7000PC474200000_39d0
_dev_dvb_adapter0_DiBcom_7000PC474200000_39e0
_dev_dvb_adapter0_DiBcom_7000PC474200000_39f0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3a10
_dev_dvb_adapter0_DiBcom_7000PC474200000_3a40
_dev_dvb_adapter0_DiBcom_7000PC474200000_3a50
_dev_dvb_adapter0_DiBcom_7000PC474200000_3a60
_dev_dvb_adapter0_DiBcom_7000PC474200000_3a80
_dev_dvb_adapter0_DiBcom_7000PC474200000_3ad0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3ae0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3af0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3b60
_dev_dvb_adapter0_DiBcom_7000PC474200000_3b80
_dev_dvb_adapter0_DiBcom_7000PC474200000_3c90
_dev_dvb_adapter0_DiBcom_7000PC474200000_3cc0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3e50
_dev_dvb_adapter0_DiBcom_7000PC474200000_3ea0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3eb0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3ee0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3f10
_dev_dvb_adapter0_DiBcom_7000PC474200000_3f60
_dev_dvb_adapter0_DiBcom_7000PC474200000_3fa0
_dev_dvb_adapter0_DiBcom_7000PC474200000_3fa4
_dev_dvb_adapter0_DiBcom_7000PC474200000_3fac
... so one per service. Opening the first of these:
Primary> more *3280*
{
"service_id": 12928,
"pmt": 275,
"stype": 1,
"scrambled": 0,
"channel": 0,
"provider": "",
"servicename": "5*",
"channelname": "5*",
"mapped": 1,
"dvb_eit_enable": 1,
"default_authority": "www.five.tv",
"pcr": 6673,
"disabled": 0,
"stream": {
"pid": 6673,
"type": "MPEG2VIDEO",
"position": 0
},
"stream": {
"pid": 6674,
"type": "MPEG2AUDIO",
"position": 1,
"language": "eng"
},
"stream": {
"pid": 6675,
"type": "MPEG2AUDIO",
"position": 2,
"language": "eng"
},
"stream": {
"pid": 6678,
"type": "DVBSUB",
"position": 3,
"language": "eng",
"compositionid": 2,
"ancillartyid": 2
}
}
The major difference I see is that my services are named - but you'd spotted this earlier, so nothing new there!
What I haven't done, and what you might try if you have another Linux box around, was to copy the services and/or channels over from a different TVH installation. The same tuner, the same muxes, the same transmitter... the files should be identical. So you could at least compare and, if they're more promising on a different machine, maybe try using those instead?
Sorry, though, I'm not sure that's really much help (beyond me now knowing how to get tvheadend running on a Synology...!).
EDIT
Another random thought - what if you shut down tvh, and then manually name the service in these files before restarting?