Station Connection Failures

[NukeJets]

There are four stations that show errors upon loading. They are:

earthquakescanada.nrcan.gc.ca

sislink.geofisica.ufrn.br

rtserve.ida.ucsd.edu

cwbpub.cr.usgs.gov

Is this a common occurrence? Is there anything I can do on my end to resolve the issue?

Thanks.