A 403 and a 407 are different failures. Read the headers first.
Which layer refused your proxied request, told from four details in the response: the status line, the challenge, the signature and the body.
10 min read
Troubleshooting
Working notes on proxies, scraping and the network behind them, written by the people who run it.
Ask the network
See pricingRead about the network, then try it.
Every article here is written from what we can measure or cite. If your job needs a pool or a Mac, the pricing page is the short version.