DSL router blocking thumbnails

I changed my ADSL router with a wireless one, because our little dog had some chewing issues lately and ate all my UTP cables one by one. As a friend told me “Our little dog brought technology at home”.

Because I was to lazy (and out of money) to buy a new one, I borrowed a Philips  CGA5720s wireless router from axaristos. It is a ANNEX-B modem router that otenet shipped with new adsl connections in the past. It isn’t supported by Philips, thought!

The first issue was that my line is ANNEX-A (PSTN) but I was planning to use as a simple Wireless AP along with my old ADSL modem. Happily enough I found in the web that with a firmware upgrade Philips CGA5720s can be converted to ANNEX-A.

Simple process and all worked perfect.

But after some days I noticed that some websites ( e.g. Yahoo! Images, Booking.com ) had trouble showing me the thumbnails. Checking my routers logs I noticed some **SYN Flood to Host** errors when accessing these sites.

Hopping around the web I found to resolutions for the issue.

In the router web interface go to Security -> Firewall -> Intrusion Detection

  • disable SPI and Anti-DoS firewall protection

or if you don’t want to disable completely Intrusion Detection you can try changing the following values

  • Maximum incomplete TCP/UDP sessions number from same host (default: 10): 50
  • Incomplete TCP/UDP sessions detect sensitive time period (default: 300): 750 msec

And that’s it!

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