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Can I configure a Cisco switch between 2 WiFi routers?


I have an ISP WiFi router that is limited to only one port, even though there are 4 ports on this ISP's router.  Please refer to the diagram:




(1) The yellow router is a TP-LINK AC1750 (A7) situated in another house 50 meters away.

(2) the 2 cabling connections (in red) from/to the Cisco switch are Cat6 cables.

(3) 2 recommendations were given to me:

(3a) configure a routed port on the Cisco switch, and then connect the Cisco switch from the LAN port configured as a routed port to a LAN port on the yellow router.  The WAN/Internet port of the yellow router must NOT be used for this connection.  The users connecting to the yellow router need only one functionality:  to connect to the Internet.  They don't need to access anything server or device connected to the Cisco switch which is in the main house about 50 meters away.

(3b) configure a VLAN on the Cisco switch.  Then from the port associated with the VLAN on the Cisco switch, connect to the WAN/Internet port of the yellow router.

I'd be grateful for any tips, guidance and/or comments on this problem. and the 2 recommended solutions.


I also ordered a Cisco SG300-20 switch (actually it has some Layer 3 routing capability), because I found out that the SG110-16 is an unmanaged switch, giving me doubts about its ability to configure either a VLAN (3b solution) or a routed port (3a solution).


Thanking you all in advance.

VIP Mentor



what is the result of implementing the two recommendations that you have been given ? What does (not) work ?


Thank you for replying -- I have not been able to try out any of them just yet.

The orders I placed for the switches adn WiFi routers are taking weeks (now over a month) to ship due to Covid.

I thought checking it out in advance is the only thing I can do at this time.

Many thanks.

VIP Mentor

i would advise here for 3B is the right option for your to extend the VLAN, But on Switch what server is connected ? 


1. on the Yellow Router is this only Wifi Connection ? then they may have different IP address  space right ?

2. So you can have restriction in place to not to communicated with Servers connected in Switch.


SG-300 is the reasonalble product.

*** Rate All Helpful Responses ***

Thank you BB for responding.

The Cisco switch has about 3 (old fashioned PCs, i.e., desktops) connected locally.  They just run Office, email and connect to the Internet occasionally.  Then about 4-6 laptops with WiFi in the Main Building (boundary shown in the dotted square) doing more or less the same, but mostly surfing the Internet.  No servers.


On your (1) question, I am not sure I understand.  yes, it is the only WiFi router connected to the Cisco switch.  But if a need arises, is there anything to prevent me from installing another one in another such location?  Would this not be a matter of defining another VLAN (if the recommendation 3b stated in my original post is taken).


On your (2) comment, I take it you mean that the VLAN for the yellow router is isolated from the rest of the LAN traffic on the Cisco switch.


Thank you.


if they are normal user PC  - I would not see any issue here.


I prefer to have only extended same VLAN, so Wifi router (yellow get IP address form Red router) - switch act as L2,


On the Yellow Router for Wifi user you can have your own IP address pool.

*** Rate All Helpful Responses ***

Thank you BB ... if I understand your comment correctly, yes, the intent is for the yellow router to:


(a) route only among its wireless -- and wired, if any -- clients in that remote house 50 meters away;

(b) use the Cisco switch only as a "pass through";

(c) have none of its traffic going to the Cisco switch interfere (or be "heard") by all the other devices connected to the Cisco switch;

(d) access the Internet through the ISP WiFi router (colored red).


But DHCP on the yellow router must be disabled (I think), otherwise it conflicts with the red router (?), which must be the only DHCP server on this entire LAN.  The other "compicating factor" is that if a Cisco SG 300 switch is used, this device also has some L3 routing capability, including acting as DHCP server and IPv4 routing.  This is where it gets murky.