Error: uplink is offline

[umaxfun]

Hi,

From time to time I'm encountering strange issue: Sinopia logs say that "uplink is offline". It continues several minutes and after that everything is ok again.

http  <-- 500, user: undefined, req: 'GET /underscore/-/underscore-1.7.0.tgz', error: uplink is offline
 http  <-- 500, user: undefined, req: 'GET /mime-db/-/mime-db-1.25.0.tgz', error: uplink is offline
 http  <-- 500, user: undefined, req: 'GET /bytes/-/bytes-2.4.0.tgz', error: uplink is offline
 http  <-- 500, user: undefined, req: 'GET /transformers/-/transformers-2.1.0.tgz', error: uplink is offline
 http  <-- 500, user: undefined, req: 'GET /jison/-/jison-0.4.13.tgz', error: uplink is offline
 http  <-- 500, user: undefined, req: 'GET /mongodb-core/-/mongodb-core-1.1.20.tgz', error: uplink is offline
 http  <-- 500, user: undefined, req: 'GET /mongodb-core/-/mongodb-core-2.0.13.tgz', error: uplink is offline
 warn  --> host registry.npmjs.org is back online
 http  --> 200, req: 'GET http://registry.npmjs.org/readable-stream/-/readable-stream-2.2.1.tgz' (streaming)
 http  <-- 200, user: undefined, req: 'GET /readable-stream/-/readable-stream-2.2.1.tgz', bytes: 0/20269
 http  --> 304, req: 'GET http://registry.npmjs.org/once', bytes: 0/0
 http  <-- 304, user: undefined, req: 'GET /once', bytes: 0/0
 http  --> 304, req: 'GET http://registry.npmjs.org/dom-serializer', bytes: 0/0
 http  <-- 304, user: undefined, req: 'GET /dom-serializer', bytes: 0/0
 http  --> 304, req: 'GET http://registry.npmjs.org/process-nextick-args', bytes: 0/0

"Uplink is offline" right now, but github is loading, music is playing and registry.npmjs.org is accessible from local machine.

How can I debug this issue?