I'm having a problem getting 21 Mbps (actual download speed) out of my Toshiba L655-S5065 with a Realtek RTL8191SE NIC. It only reaches max 3 Mbps down and 2 Mbps up (that's normal). Other laptops on my network are able to reach those speeds. They're link speeds max out at 144.5 Mbps whereas this laptop maxes out at 72 Mbps. Strangely I receive faster speeds on this laptop (the slow one) when I change my Linksys E1500 to b/g only. That ends up slowing the other laptops down which are running at full N-speeds. I spoke to Realtek about this who were not able to help and rudely stopped responding to me. I tired getting on Toshiba's forums but I'm not receiving a confirmation e-mail for my account (right address). Is it possible to buy and install a different NIC card instead, as in NOT a Realtek? I have a N-usb adapter but would rather not have something protruding from the pc all the time.
Wireless is always a tricky thing to troubleshoot. You could replace the Realtek card with a different wireless card, since it uses Mini PCI-e. Try an Intel or Atheros based card like the Intel Advanced-N 6300 or Atheros AR5008.
Make sure your router is set to the right protocol. Whatever the fastest speeds in your area are - (Global, 1XRTT, EvDO, LTE) is what it's WWAN setting should be. If you reset the router, it can revert to a slower setting.
For example; ours normally serves at 1.4Mbps, but if reset drops to 40Kbps.