You did create a loop by assigning all ports to two VLANs with the setup outlined in #3 (ports 1 to 8 in VLAN 1).

To share an Internet connection on port 1 with two VLANs 2 and 3, port 1 must be a member of VLAN 2 and 3, but ports in VLANs 2 and 3 may not be members of VLAN 1. Whats more, your router on port 1 must be able to receive and send VLAN-tagged packets in order to be able to communicate with devices in both VLANs 2 and 3. So port 1 must be a tagged port.

See http://www.tp-link.com/us/faq-544.html for an example of two VLANs sharing a common Internet router. It uses two switches, but you can adapt this example to only one switch too.

In port-based VLANs assigning a port into more than one VLAN usually makes this port a trunk port, so it is not an access port anymore (no matter what it's PVID is). The TP-Link example in the mentioned FAQ uses access ports 2-3 in VLAN 100 and 4-8 in VLAN 101. By assigning port 9 into VLANs 100,101 and 102 it will become a trunk port, i.e. it requires tagged packets on input to be able to forward them into the destination VLAN. Just ignore the port 1 and the second switch in the example given in the FAQ, it's not important for the use case discussed here.

Anyway, in order to access two separate VLANs through one cable over a trunk port, your connected device (Internet router) must be able to send/receive tagged packets.

Just imagine you would use two cables to your Internet router, one from the switch's access port 1, another from access port 8. You would assign ports 1-3 to VLAN 2 (Home) and ports 4-8 to VLAN 3 (Apartment). Then you plug both cables from ports 1 and 8 into two LAN ports of your Internet router. Without separating this two LAN ports of the Internet router into two different subnets - one for Home, one for Apartment -, you would create a "loop" or more precisely, one big Home-Apartment-LAN out of two VLANs. Makes no sense to me. So, if you want to share a common resource between two VLANs you either would have to use two subnets on the Internet router and two cables to the switch's access ports or one cable to a trunk port using tagged packets.

AFAIK there is no way with the TL-SG108E to connect two separate VLANs over one physical access port/cable with two or even one common subnet. It must be a trunk port to do so. If I'm wrong, pls correct me and give an example of a working setup, I would be glad to try it out.

Of course there are alternatives such as VLAN-routing or multi-mode ports in more expensive switches, but - according to my knowledge - not in the TL-SG108E.

glasser wrote

TP-Link already has a Version3 in the pipe as seen on their support site... that is if you care to debug their design by trials! TPLink routers are mostly great, unlike the chip vendor behind the 108EV2!!

I'm not sure wether V3 will actually change anything except a new user interface with the new TP-Link logo. ;)

I first ordered a TL-SG108E and got V1 without a web UI, but with a "Configuration Uitlity" running on Windows only :mad:. Oh boy, I never ever used Windows in 40 years IT. I did read the whole manual before, but the German branch of TP-Link did by accident publish the V2 manual long time before the device was available. So I did send the switch back and asked TP-Link sales for V2, which was delivered more than a half year later. AFAIK it had the same features as V1, but a web UI - thanks TP-Link God :D. I also just returned a TL-SG108PE V1 with an old firmware version because of the same reason and now I'm waiting for the V2 replacement of this model.

However, I use the two TL-SG108E and one TL-SG2008 only for simple trunking of several VLANs at my home and home-office and a T1600-24TS in the machine room for doing all fancy things in between (mostly learning to be able to sell this gear to my customers). The T1600 was affordable for my small budget and it can do a lot more such as VLAN routing and multi-nets NAT, which can help in sharing resources in different VLANs.

If you could do this with a TL-SG108E - would be even better. But so far from my understanding and practical experience with this device, the TL-SG108 has only very limited features compared to the more expensive switches. That's not bad - a lot of people needs such a cheap switch, e.g. for VLAN-based Multi-SSID setup of WiFi gear.