I looked in the cef3.log and this is a snippet of the first part of it if that helps ( ie a lot of blocked proxy going on there)
[1109/145937:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for accountportal-website-prod07.ol.epicgames.com:443.
[1109/145937:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for accountportal-website-prod07.ol.epicgames.com:443.
[1109/145943:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for www.epicgames.com:443.
[1109/145943:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for launcher-website-prod07.ol.epicgames.com:443.
[1109/150003:WARNING:raw_channel.cc(210)] Shutting down RawChannel with write buffer nonempty
[1109/150003:WARNING:raw_channel.cc(210)] Shutting down RawChannel with write buffer nonempty
[1109/150003:WARNING:pref_notifier_impl.cc(27)] pref observer found at shutdown proxy
[1109/150129:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for www.epicgames.com:443.
[1109/150130:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for launcher-website-prod07.ol.epicgames.com:443.
[1109/150430:WARNING:raw_channel.cc(210)] Shutting down RawChannel with write buffer nonempty
[1109/150430:WARNING:raw_channel.cc(210)] Shutting down RawChannel with write buffer nonempty
[1109/150430:WARNING:raw_channel.cc(210)] Shutting down RawChannel with write buffer nonempty
[1109/150430:WARNING:raw_channel.cc(210)] Shutting down RawChannel with write buffer nonempty
[1109/150430:WARNING:pref_notifier_impl.cc(27)] pref observer found at shutdown proxy
[1109/151557:WARNING:http_network_transaction.cc(359)] Blocked proxy response with status 407 to CONNECT request for accountportal-website-prod07.ol.epicgames.com:443.