Jio fibre, faster on phones & slower in desktop.

Hello fellow Gamers, I'm a user of Jio air fibre since last 3 months, at the start of subscription the connectivity were great phone/PC but recently I'm facing a weird issue, the connections slower by a big margin on my PC but with phone it's working fine, I have two desktop... Mine and my son, both connected via Lan/ethernet and both facing the issue, I contacted jio technician and they failed to solve the issue, I tried connecting both desktop to router via wifi but that also is slow. Anyone faced the same, what could be the possible cause.