server: provide helpful workaround hint when stalling on pull (#3584)

This is a quick fix to help users who are stuck on the "pull" step at
99%.

In the near future we're introducing a new registry client that
should/will hopefully be smarter. In the meantime, this should unblock
the users hitting issue #1736.

server/download.go

@@ -247,7 +247,8 @@ func (b *blobDownload) downloadChunk(ctx context.Context, requestURL *url.URL, w
 				}
 
 				if !part.lastUpdated.IsZero() && time.Since(part.lastUpdated) > 5*time.Second {
-					slog.Info(fmt.Sprintf("%s part %d stalled; retrying", b.Digest[7:19], part.N))
+					const msg = "%s part %d stalled; retrying. If this persists, press ctrl-c to exit, then 'ollama pull' to find a faster connection."
+					slog.Info(fmt.Sprintf(msg, b.Digest[7:19], part.N))
 					// reset last updated
 					part.lastUpdated = time.Time{}
 					return errPartStalled