Netflix has stopped working when devices are connected through switch

[Retired_Member]

Hi, last week, after working fine for many months, Netflix stopped working on any devices that are connected to my cable modem via my Netgear GS108 unmanaged switch. 

Netflix still works absolutely fine on devices with a direct wired connection to the modem (i.e. my desktop computer) and Netflix stills works fine on devices with a WiFi connection to the modem (2 mobiles phones, a Microsoft Surface tablet).
However on a Sony Android television, a Sony UHD BluRay player, and an Oppo BluRay player, Netflix now gives error NW-2-5 when these devices are connected through the Netgear GS108 switch. (All their other network functions and diagnostics appear to be fine).
If connect the television or either disc player directly to the cable modem, bypassing the GS108 switch, Netflix works fine again.

I'm baffled as to why the Netgear switch has stopped working with Netflix, anyone have any suggestions? (I don't think it has anything that can be configured!)
I have tried switching everything off and back on again, of course 🙂

[Retired_Member · Accepted solution]

Well, I fixed it.

The firewall settings had been changed on my Hyperoptic 'home gateway' (cable modem/router).  

[antinode]

> [...] any devices that are connected to my cable modem [...]

   Not a very detailed description of anything.  What is your "my cable
modem"?  Is it a modem, or a modem+router?

> [...] when these devices are connected through the Netgear GS108
> switch. [...]

   "when these devices are connected" _to_ _what_ "through the Netgear
GS108 switch"?

   What, exactly, is connected to what, exactly?  (Hint: If a device has
multiple Ethernet ports, then "connected to device" is not enough
detail.)

   If your (unspecified) "my cable modem" is a modem (not a
modem+router), then you can expect trouble if you connect multiple
devices to it through a network switch.  Your (unspecified) cable-TV ISP
service probably allows you one public IP address, which will be granted
to the first of your gizmos which they see.  After that, there'll be a
fight over that one address, leaving all but one device unsatisfied.

   If your (unspecified) "my cable modem" is a modem+router, then you
should be able to connect many devices to it through a network switch.

> I have tried switching everything off and back on again, [...]

   Swell.  What _is_ "everything"?

[Retired_Member]

> What is your "my cable modem"?  Is it a modem, or a modem+router?

It's a ZTE ZXHN H298A V1.0 V1.0.25_HOP.1T3 supplied by https://www.hyperoptic.com

> "when these devices are connected" _to_ _what_ "through the Netgear GS108 switch"?

When my television, two disc players and a home cinema amp are all connected to the GS108 switch, which is in turn connected to a LAN port on the ZTE modem.

> then you can expect trouble if you connect multiple devices to it through a network switch....

Yeah, but everything worked fine for months until last week. 🙂   (Which suggests either my ISP pushed out some firmware or config change, I guess, or Netflix changed something at their end...)   On the admin dashboard page for the modem, I can see all four devices have been assigned a unique IPv4 address by DHCP.

>   Swell.  What _is_ "everything"?

42, of course.

But also: the ZTE modem, the Netgear GS108 switch, a NAS, my desktop PC, two mobile phones, a Kindle, a television, two BluRay players and a home cinema amp.  All of which, when powered back up in a sensible order, appeared to obtain connectivity fine, except that Netflix wouldn't work on the ones going through the GS108 switch. 

[Retired_Member · Accepted solution]

Well, I fixed it.

The firewall settings had been changed on my Hyperoptic 'home gateway' (cable modem/router).