My question is if such a setup would work:
A cable modem, several LAN machines as well as the router/server (Linux box, with just 1 port) connect to a cheap smart managed switch such as the TP-Link TL-SG108E. The LAN machines should be able to connect to the Internet through the router.
Can such a switch be configured such that the LAN machines receive untagged traffic, but the router will receive their traffic e.g. with VLAN ID 1, and that the modem will also receive untagged traffic, but the router will receive its traffic e.g. with VLAN ID 2?
Additionally, are there any security or performance considerations*?
*) I am aware that since the router uses just 1 port the bandwidth would split between LAN and WAN traffic. For that I'd do shaping on eth0 in both directions according to my needs.