What server issues might cause temporary and repeated Soft 404/500 Errors that appear to be functioning correctly when checked later from Google Webmaster Tools?

[StaffingRobot]

We are experiencing unknown server issues (we think) which are causing Soft 404/500 errors at unpredictable times on 2 websites. When we check on the pages, they’re fine but still show errors in Moz/Search Console.

What are some measures we can take to protect from this or figure out what is causing this?

Example URL for Soft 404 Error: https://www.advancedtraveltherapy.com/jobs/any/occupational-therapist/any/

Example URL for 500 Error: https://www.advancedtraveltherapy.com/job-detail/ms/physical-therapist/87529740/

Example URL for Soft 404 Error: https://www.advancedtravelnursing.com/search/searchresults.php?jobState=CA&tempType=g&specialties=

Example URL for 500 Error: https://www.advancedtravelnursing.com/job/ma/registered-nurse/emergency-room/87108662/

[badgergravling]

It could be an intermittent slow server or one that's dropping out occasionally. There are various services which allow you to monitor uptime (e.g. Pingdom etc).