Noriu pasidalinti savo patirtimi, apturėtą šiandien atnaujinant Linksys 
BESFR41 routeriuką. OS - Vista Ultimate 64 bitų. Gal kam bus naudinga.

1. Klaidą, kurią padariau, tai firmware atnaujinau per Internet Explorer 
sąsaja :) Aišku, po atnaujinimo nebegalėjau prieiti prie routerio nustatymu 
ir mirksėjo maitinimo ledas. Tada prasižaidžiau gal tris valandas bandydamas 
prisijungti prie savo routerio. Kol dar kartą neįlindau į google ir radau šį 
paaiškinimą:
 "On the subject of Error Code 1231, this could be one of many problems. 
None of which include the router itself except for one, indirectly.  The 
first problem is corrupted hardware and drivers, the simple solution to that 
is remove the network card reboot then downboot then install it and reboot 
reinstalling it or if it's built in just install reboot and reinstall.  The 
other of which is a problem that stems from Vistas ready-ness for lack of 
internet assigned addresses and your DCHP hating the fact that Vista prefers 
IPv6 over IPv4 so it's trying to strap to IPv6 and your router is telling it 
to go away because it either doesn't translate correctly or flat out doesn't 
accept it.  The solution to that is simply disable IPv6 on that interface 
and try to reconnect in an elevated command prompt doing ipconfig /renew. 
Make sure you also have the latest firmware to confirm that this isn't the 
issue.  I am assuming you are on Vista based on the amount of router trouble 
you are having and the error code"

2. Nuo šiol routerį atnaujinsiu tik panaudodamas tftp.exe
3. Ir Vistoje nepamirškite atjungti IPv6 (nuimti varnelę) atnaujinant 
routerio firmware. Kol to nepadariau, routeris buvo nematomas.

Kaip reikia elgtis bendrai, kai firmware nepavyko įkelti, rasite čia: 
http://forums.linksysbycisco.com/linksys/board/message?board.id=Wireless_Routers&thread.id=41646&view=by_date_ascending&page=1