Cannot open some sites randomly

I have OnePlus 7t running on oxygen os 10.3.3.. yes you read it right. Still 10.3.3. But since last couple of months I am facing a weird issue. Phone randomly stops connecting to only certain websites or servers. Then I have to restart the phone and it starts connecting again. Then after around 12-15 hours or a day, the same issue happenes.. so I am restarting my phone everyday when I face this issue.

For example: it may not connect to Google.com, or it may not load anything on the reddit app, sometimes it doesn't load comments on Instagram but other posts work fine.

Is this issue with modem of the device? Anyone else ever faced this?