I have received some requests for running phpipam on synology, I personally don’t use it, but if you do you will find this useful.

Apparently the problem is in missing GMP php extension, you can find it here, along with instructions:
http://forum.synology.com/enu/viewtopic.php?f=34&t=101226&p=401309#p401309

thanks to Ferdinand for providing extension.

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