Have you tried doing the following procedure ? :
1.) Perform a hard reset on the router to bring it back to factory defaults.(See bottom of P.82 in the User Manual for procedure.)
2.) Manually enter all the configuration data and save to the non-volatile memory in the router. Please DON'T upload the configuration file on your PC's hard drive to the router.
3.) Re-run the NameBench utility and check the results.
4.) If the results are the same as before, I would then re-flash the firmware and manually reenter the configuration data and save. (DON'T upload that old configuration file !)
5.) Perform step 3 above.
6.) If the results are the same as before, I would try another DNS benchmarking utility such as Steve Gibson's DNSBench which is free and can be downloaded from the following link:
www.grc.com/dns/benchmark.htm I have used this utility and got a different set of results than when using NameBench.
Good Luck!
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Regards,
Magnetron1