WiFi connected, after some time internet stops working

Question

After I load Ubuntu, I can browse internet for some time (minutes - one hour) and than it stops working. I am still connected, but the pages do not load. If I disconnect and reconnect to the WiFi, I can load a fraction of a page but then it stops again. At work I can connect and browse for hours without problem. I searched this topic a bit and it seems like many people have the same problem but I haven't found any solution. Please help.

This are some of my parameters:

*-network     

   description: Ethernet interface
   product: 82567LM Gigabit Network Connection
   vendor: Intel Corporation
   physical id: 19
   bus info: pci@0000:00:19.0
   logical name: eth0
   version: 03
   serial: 00:22:68:15:33:57
   capacity: 1GB/s
   width: 32 bits
   clock: 33MHz
   capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=1.0.2-k2 firmware=1.8-3 latency=0 link=no multicast
   resources: irq:29 memory:fc600000-fc61ffff memory:fc625000-fc625fff ioport:1840(size=32)

*-network

   description: Wireless interface
   product: Wireless WiFi Link 5300
   vendor: Intel Corporation
   physical id: 0
   bus info: pci@0000:03:00.0
   logical name: wlan0
   version: 00
   serial: 00:21:6a:76:2e:ae
   width: 64 bits
   clock: 33MHz
   capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
   configuration: broadcast=yes driver=iwlagn ip=192.168.2.8 latency=0 multicast=yes wireless=IEEE 802.11abgn
   resources: irq:32 memory:f4200000-f4201fff