IPv6 Prefix Lifetime

Can anyone confirm AirLink gateways are modifying the IPv6 prefix lifetime(s) when forwarding ISP ICMPv6 Router Advertisements (RA) to LAN clients?

ES450 and RV50X running latest GA release are both setting the valid lifetime to 30s and preferred lifetime to 20s w/in the RA prefix info option. When moving the T-Mobile data only SIM to a non-Sierra devices (Franklin T9/10) to validate these are the actual ISP values, they differ. Valid/preferred lifetimes are set to infinity (4294967295) on the Franklin T9 and T10’s tested.

IP6 (hlim 255, next-header ICMPv6 (58) payload length: 104) fe80::214:3eff:fexx:xxxx > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 104
  hop limit 64, Flags [none], pref high, router lifetime 9000s, reachable time 1000ms, retrans timer 0ms
    prefix info option (3), length 32 (4): 2607:xxxx:xxxx:xxxx::/64, Flags [onlink, auto, router], valid time 30s, pref. time 20s
    rdnss option (25), length 40 (5):  lifetime 10s, addr: fd00:976a::9 addr: fd00:976a::10
    mtu option (5), length 8 (1):  1430
    source link-address option (1), length 8 (1): 00:14:3e:xx:xx:xx

Having issues w/ mobile (primarily Android) LAN clients losing IPv6 connectivity and I suspect these short RA lifetimes paired w/ device sleep/battery conservation may be the root cause, as noted possible under RFC7772. RFC 7772: Reducing Energy Consumption of Router Advertisements

When these mobile devices are connected to the Franklin devices these issues disappear.

Why is AirLink apparently modifying these values?
Has anyone observed similar behavior?