That error message is definitely more "Matrix-level" technical than what you'd expect when just trying to sell a pair of shoes or a vintage camera.

In plain English, it's not you, it's them. Specifically, this is a server-side error happening within eBay's infrastructure (or their service provider's).

What the Error Actually Means

The "upstream connect error" indicates that the front-end server you're hitting is trying to talk to a back-end database or service to process your response, but that back-end service isn't picking up the phone.

• Error 111: This is a standard "Connection Refused" code.
• The Cause: eBay's servers are likely overwhelmed, undergoing maintenance, or experiencing a temporary "hiccup" in the specific module that handles offers.

How to Fix It

Since the issue is on their end, you can't "fix" it with settings, but you can bypass the glitch:

1. The 10-Minute Rule: Most of the time, these "transport failures" resolve themselves within minutes as traffic balances out. Wait a bit and try again.
2. Switch Platforms: If you are using the eBay App, try responding via a mobile or desktop browser (and vice versa). Different platforms often hit different server clusters.
3. Clear the Cache: If you're on a browser, try an Incognito/Private window. Sometimes a "stale" cookie tries to force a connection to a specific server that is currently down.
4. Check eBay System Status: If it persists for more than an hour, check a site like DownDetector to see if there is a localized outage affecting other sellers.

Pro-Tip: If the offer is expiring soon and you can't get through, don't panic. You can usually message the buyer directly from the item page to let them know you're trying to accept but the system is acting up-it keeps them from thinking you're ghosting them!