UPDATE
they didn't turned the bridge mode on and there technician also know how to do it then one sir gave contact of pune's airtel technician talked to him he guided me and i saw the option of bridge mode in WAN2 in wan connections but when i enabled it and deactivated the WAN0 (PPPoE) and entered the ID and Password same as i seen in WAN0 and dynamic ip was on but still the internet is not workin' can anyone explain in step by step method i'd be grateful thank you for reading.
edit : lan cable that i got in
Netgear router when i purchased it i used that for connecting two router ( netgear = wan port | airtel router = lan1,2,3,4 ) tried every port didn't work.