Why is network IP address is assigned to WAN of MX68 ?

[K-C]

I have xxx.xxx.xxx.176/29 as global IP address range from ISP provider and set WAN of MX68 as auto-IP-assign with PPPoE authentication.

1. Somehow, MX68 is assigned with not host address but network address, xxx.xxx.xxx.176/29. Is this specification of Meraki?

2. And, might this assigned IP address be changed to another IP address within the global IP address range in the future?

Thank you,

[ww]

This should be  assigned/offered by the isp. So i think you have to ask them