Believe me that I have almost tried everything to try to solve the routing issues with my airtel g140w-f
Tried both google's and cloudflare's DNS, bridge mode (PPPoE and static IP), tried linux, windows and iOS devices, different routers, different Ethernet adapters(intel and realtek) and cables
Tried getting the g140w-f from airtel replaced as well
The routing through the wifi of ONT(g140w-f) is different as compared to Ethernet (bridge mode as well as routing mode)
Using wifi of ONT, everything works perfectly but while using Ethernet, routing gets weird
I have tested the same with my cousin's connection as well in noida with Nokia g140w-f and same result
Even something like bridge mode is different based on how exactly it's enabled by the backend team, sometimes you can establish unlimited number of pppoe connections using bridge mode.
i Had complained on this issue , they couldnt find what was issue and finally gave up and closed the ticket, but they informed a global ticket will be raised to follow up on this. now the issue seems to have resolved at least for me. no more buffering at my end in youtube.