cURL error 56 — CURLE_RECV_ERROR, usually shown as "Recv failure: Connection reset by peer" — means the connection was up and then something actively killed it mid-transfer. Unlike a timeout, this is a deliberate reset, not silence. The fix depends on who sent it: the target server, a firewall or NAT device in the path, or the proxy enforcing its access rules.
Error 56 is CURLE_RECV_ERROR: curl had a working connection — TCP established, usually TLS complete, request often already sent — and then a read on the socket failed. The most common form is "Recv failure: Connection reset by peer", meaning something transmitted a TCP RST and tore the session down. Where error 28 is silence and error 7 is a refusal to start, 56 is an active kill of a connection that already existed.
Reset senders fall into three groups. The target server: a crashed worker, a restarting backend, or an anti-bot layer that accepts the connection and then resets it once the request looks automated. An intermediary: stateful firewalls and NAT devices expire idle sessions mid-transfer, intrusion-prevention systems kill flows they dislike, and VPN MTU problems break large packets while small ones pass. Or the proxy: access-control rules and connection-lifetime limits can both end in a reset.
Timing is your best clue. A reset immediately after connecting suggests an access decision. A reset after the request is sent suggests content-based filtering. A reset minutes into a download suggests idle timers or lifetime limits. And an intermittent reset on the first request of a batch is the signature of a stale keep-alive socket reused after the far end already closed it.
Note when the reset fires and whether it is consistent, then walk the list — the pattern usually names the culprit by step three or four.
Connection: close, or make your client retry once on a fresh connection when a pooled socket dies on first read.-v and note how far it gets. A reset before response headers implicates access control or anti-bot filtering; a reset mid-body implicates idle timers or transfer limits.https://api.ipify.org. Success there clears the proxy leg and moves suspicion to the target.-C -, split work with range requests, and set --keepalive-time 30.A proxied transfer has two TCP legs — you to the proxy, and the proxy to the target — and a reset can originate on either. Resets that arrive before any response usually reflect an access decision on the near leg: the classic case is IP-whitelist authentication after your public IP changed, because your office moved, a VPN toggled, or your ISP reassigned a dynamic address. To the client, that policy decision looks identical to a broken server.
Resets after the request is sent usually come from the far leg. Anti-bot systems commonly allow the connection and handshake, then reset once the exit IP has accumulated bad reputation or the traffic pattern trips a rule. The practical response is rotation: a fresh exit clears a burned IP, while sticky sessions keep a known-good exit stable for the jobs that need continuity.
ProxyOmega supports two auth modes: username/password, where the password is your dashboard API key, or IP whitelist. Whitelist auth is convenient until your egress IP changes — then every connection resets. If your IP is dynamic, use credential auth, which works from any address; if it is static, keep the whitelist current in the dashboard.
Resets that appear on one exit and vanish on the next are reputation, not infrastructure. Budget Unlimited (/plan-unlimited/) ports rotate exits on a per-port interval automatically; to force a fresh IP on demand, start a new sticky session by changing the -session- value in the username.
Large downloads are the most exposed to idle timers and connection churn. Pin the exit with a sticky session — held for up to 24 hours — so retries and range requests resume through the same IP, and combine that with curl's resume flag so a reset costs you one byte range instead of the whole file.
This request pins a sticky exit so every retry uses the same IP, keeps NAT state alive during long transfers, resumes after interruption, and retries automatically — turning a fatal reset into a recoverable pause.
# Sticky exit + keepalive + resume + retries
curl -x "http://USERNAME-session-job42:[email protected]:10000" \
-H "Connection: close" \
--keepalive-time 30 \
--retry 3 --retry-all-errors --retry-delay 2 \
-C - -o report.pdf \
-sS "https://example.com/files/report.pdf"Connection: close, shorten pool idle time, or retry once on a fresh connection — a single clean retry usually makes this class of reset disappear.-session- username flag. Enable resume with -C - so a reset costs a byte range instead of the file, and set TCP keepalive to survive NAT idle timers.Rotate off burned IPs or pin a sticky exit for up to 24 hours on ProxyOmega's 90M+ IP network.
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