I'm having an odd issue where intermittently I can't access LAN devices (Sonos, NAS drive, Wifi thermostat etc) when connected via Wifi to a Draytek Vigor2862ac Router. The Sonos and NAS are all connected to the Router via a single Ethernet port. I also have a couple of AP902 access points connected to the router via one Ethernet port and I have no problems connecting to LAN devices when connected to these via Wifi.

Network is like this:
Vigor2862 Router
--ethernet cable-->
* NETGEAR JGS524PE 24-Port switch in loft
** --ethernet cable--> NAS drive
** --ethernet cable--> Sonos
** --ethernet cable--> AP902 Wifi access point
*** --Wifi--> Another Sonos
*** --Wifi--> Thermostat

I have multiple SSIDs:
- Main one which allows roaming around all access points and the router. Connected to LAN1
- Guest SSID on LAN2 which is isolated from LAN1. Guest SSID on the AP902 accesspoints is routed via VLAN1 with VID1
- SSID for each access point / router at 2.4Ghz on LAN1
- SSID for each access point / router at 5GHz on LAN1

Therefore I can switch between SSIDs, however the problem seems to remain for a while and then suddenly starts working. All the time I still have internet access.

Any advice on either what the problem might be, or what I should do next time I discover it to try and debug the problem?

Thanks,
Gary

I am wondering if it would be any more stable, if you add a specific VLAN tag to LAN1 as well (using the NETGEAR JGS524PE to add the tag for the Sonos, thermostat etc, that can't do it themselves). That way, the switch and router should be in no doubt, as to what's allowed to communicate with what.

I'd admit that I have a fairly low confidence that this is the answer ... but it's the best you've received so far

Otherwise, I foresee a lot of port-mirror'ing and wire-sharking ahead of you

(I've just tangled with a VLAN related issue involving a Netgear switch, a Vigor 2860 and a Sky Q box - I know what I did to 'fix' it, but I don't understand my fix...it involved setting the 'PVID' (default VLAN) for untagged & priority traffic, on the Netgear. Wireshark revealed that DHCP from a SKY-Q box fits this bill, but nothing else that's ever been plugged in there does!)