Error 503 repeated response on MFC

  • HI
    Thisis my first time in this forum, so maybe this is not the right category. But I really need help with this.
    I have a VXA1002 appliance, i use it as cache proxy. Since a while it is not working propertly. When i try to navegate through it, i receive an error 503 response for all sites. the accesslog shows code 503 and subcode 71001 (wich not appears in the documentation). I’ve confirmed it is not a problem of resources configured for the resource pool or maximum number of configured sessions limitations.
    This is an example of service log i get:

    internal - [13/Apr/2017:15:29:48 +0000] GET HTTP/1.1 503 0 tproxy 71001 0 0.0 0.0 - - - - - - - - - mfc

    This behaviour is erratic. sometimes, after i restart the device it begins serve pages well, but after a couple of minutes it starts to behave as i explained before. If you could give me some advise it will be great. I’ve tried eveything (even reset to factory defaults) but nothing works. Thanks in advance.