So the setup is like this:
My main router is an ADSL WiFi router which also has an inbuilt network switch. All switch ports are utilized, connected to various devices via ethernet.
I decided to take a CAT5 to my 3rd floor where the plan was to connect that to a portable router (TP-LINK MR3020) which could be hooked up as and when needed.
Since all ports of the router are used, I got a switch (also TP-LINK TL-SG105). I connected the switch to the 5th port of the ADSL router after removing one device and connected that device's ethernet to the new switch. Works fine.
Now, I took the 100 ft CAT5, connected it to the new switch, took the other end up 3 floors and connected it to the portable router. The portable router isn't getting a DHCP address from the ADSL. (This is a patch cable, not a crossover cable).
If, however, I connect my portable router to the ADSL router directly, it gets a DHCP address assigned.
Any ideas why? The TP-LINK switch is supposed to have auto sensing ports, so in theory it shouldn't matter if I use a patch or a crossover cable.