Nopcommerce issue after placing behind azure frontdoor

Question

I'm using nopcommerce 4.5 currently and I've deployed it on azure web app, which is behind azure front door. Initially when it was running as azure web app there was no issues, but after placing it behind front door I'm getting below errors intermittent

1. AN ERROR OCCURRED WHILE SENDING THE REQUEST
2. The request was canceled due to the configured HttpClient.Timeout of 100 seconds elapsing

Above both errors occurring only for short time interval running schedulers, other schedulers work fine.

I'm getting this errors generally for keep alive(i.e. interval 60 seconds) and send email schedule task(i.e. interval 120 seconds).

Please advice what I'm missing, any help would be greatly appreciated.