Wifi ok mais pas de connexion internet

Bonjour,
je vous soumets un problème déjà rencontré sous ibex et que je pensais ne pas retrouver sous jaunty, c'est même pour ça que j'ai installé la bêta.

Je ne rencontrais ce souci ni avec Feisty, ni avec Gutsy, ni avec Hardy, pas non plus sous Vista ou XP (je suis en dual boot).

Le couac est apparu avec Ibex:

Pour faire simple: j'ai un portable et malgré une connexion réussie en wifi au modem routeur Netgear , je n'arrive pas à me connecter sur le Net à moins de rapprocher à qques mètres du modem, ce qui n'était pas le cas dans ce que je décris plus haut.

Je suis en DHCP et je n'ai pas de clé de sécurité.

Je ne vois pas ce qu'il faut paramétrer pour régler ce problème de distance ?

qques retours:

paglop@paglop-laptop:~$ sudo iwlist scan
[sudo] password for paglop:
lo Interface doesn't support scanning.

eth0 Interface doesn't support scanning.

wmaster0 Interface doesn't support scanning.

wlan0 Scan completed :
Cell 01 - Address: 00:0F:B5:CC:94:6C
ESSID:"NETGEAR"
Mode:Master
Channel:11
Frequency:2.462 GHz (Channel 11)
Quality=24/100 Signal level:-59 dBm
Encryption key:off
IE: Unknown: 00074E455447454152
IE: Unknown: 010582848B962C
IE: Unknown: 03010B
IE: Unknown: 2A0100
IE: Unknown: 32080C1218243048606C
Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 22 Mb/s
6 Mb/s; 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s
36 Mb/s; 48 Mb/s; 54 Mb/s
Extra:tsf=0000016029057122

paglop@paglop-laptop:~$ cat /etc/sysctl.conf
#
# /etc/sysctl.conf - Configuration file for setting system variables
# See /etc/sysctl.d/ for additional system variables.
# See sysctl.conf (5) for information.
#

#kernel.domainname = example.com

# Uncomment the following to stop low-level messages on console
#kernel.printk = 4 4 1 7

##############################################################3
# Functions previously found in netbase
#

# Uncomment the next two lines to enable Spoof protection (reverse-path filter)
# Turn on Source Address Verification in all interfaces to
# prevent some spoofing attacks
#net.ipv4.conf.default.rp_filter=1
#net.ipv4.conf.all.rp_filter=1

# Uncomment the next line to enable TCP/IP SYN cookies
# This disables TCP Window Scaling (https://lkml.org/lkml/2008/2/5/167
# and is not recommended.
#net.ipv4.tcp_syncookies=1

# Uncomment the next line to enable packet forwarding for IPv4
#net.ipv4.ip_forward=1

# Uncomment the next line to enable packet forwarding for IPv6
#net.ipv6.conf.all.forwarding=1

###################################################################
# Additional settings - these settings can improve the network
# security of the host and prevent against some network attacks
# including spoofing attacks and man in the middle attacks through
# redirection. Some network environments, however, require that these
# settings are disabled so review and enable them as needed.
#
# Ignore ICMP broadcasts
#net.ipv4.icmp_echo_ignore_broadcasts = 1
#
# Ignore bogus ICMP errors
#net.ipv4.icmp_ignore_bogus_error_responses = 1
#
# Do not accept ICMP redirects (prevent MITM attacks)
#net.ipv4.conf.all.accept_redirects = 0
#net.ipv6.conf.all.accept_redirects = 0
# _or_
# Accept ICMP redirects only for gateways listed in our default
# gateway list (enabled by default)
# net.ipv4.conf.all.secure_redirects = 1
#
# Do not send ICMP redirects (we are not a router)
#net.ipv4.conf.all.send_redirects = 0
#
# Do not accept IP source route packets (we are not a router)
#net.ipv4.conf.all.accept_source_route = 0
#net.ipv6.conf.all.accept_source_route = 0
#
# Log Martian Packets
#net.ipv4.conf.all.log_martians = 1
#
# The contents of /proc/<pid>/maps and smaps files are only visible to
# readers that are allowed to ptrace() the process
# kernel.maps_protect = 1

paglop@paglop-laptop:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

merci de votre aide