Changing the "Default Gateway" in the Router error

[PsyGeek]

Most of the times my ADSL modem router (ITI-DNA-A211-1) uses the following bsnl default gateway - 117.197.48.1 - The problem is that the i get alot of latency on counter strike 1.6 servers from India (near 350ms) while using that gateway. Now sometimes when my router is restarted due to power cut or manual restart, My router uses a different BSNL default gateway (Which happens very rarely) - 117.197.40.1 - While using this default gateway i get a lot less latency (near 50ms).
So i thought why not just change the Default gateway to "117.197.40.1" (By unselecting "Enable Automatic Assigned Default Gateway" and manually adding one). After changing the Default gateway and pressing "save and apply" I get the following error -
Configure default gateway failed.

route: SIOC[ADD|DEL]RT: Network is unreachable.

Which is weird cause i'm even able to Ping that destination, After restarting the router for the changes to take effect i'm not able to use the internet (I'm not able to access any webpage) while the "Inet" LED still glows. Now i changed my "default gateway" back to - 117.197.48.1 (Manually, not using "Enable Automatic Assigned Default Gateway") And i get the following error again -
Configure default gateway failed.

route: SIOC[ADD|DEL]RT: No such process.

To troubleshoot my problem even further i telnet'ed into my router and accessed the shell account (Busybox) and used the following command to change my default gateway to - 117.197.40.1 - "route add default gw 117.197.40.1" But still i got the same error, i tried pinging the destination inside from the shell account and i was able to ping the destination (117.197.40.1) >:/ .
How can i solve it? How can i change my default gateway to "117.197.40.1" while still making the internet work? [If u know the solution, please explain it too]

**Note - my internet works after selecting and checking "Enable Automatic Assigned Default Gateway"

 

[AgentX]

You cannot manually select any gateway you wish to use. BSNL uses automatic gateway assigning process which does it for you.You cannot set it yourself, however if you get a static IP on that gateway then you can.but hey, if you reconnect 2 to 3 times you will get the gateway you want :wewinbut if you need to restart ur modem, then its waste)Mine has a disconnect, reconnect feature in the router itself

 

[PsyGeek]

@abidh1992 Which adsl router do u have?

 

[AgentX]

I have a Linksys Cisco WAG120N Router.

It also has a auto installation feature which lets you use BSNL broadband as quick as in 3 steps without configuring too much in the router page

 

[PsyGeek]

@abidh1992 its so easy, i just have to configure the username and password in my router.

 

[AgentX]

Oh? I guess you've purchased the router so fast?

 

[PsyGeek]

@abidh1992 yes i purchased it from BSNL, adsl router.