GUA prefix not updated in client devices after router restart

when the wan interface or router is restarted, new GUA prefix gets updated on router's wan and lan interface but the client machines arent getting the updated GUA prefix. also, Active DHCPv6 Leases section in router shows the updated GUA prefix for all active clients though.

If we restart the client machine or the client interface, new GUA prefix is getting reflected. otherwise, it uses ipv4 only for internet access.

Would the issue to be at client machines, all of which were linux boxes?? pls help

Router settings:
RA - Server mode
Dhcpv6 - server mode
ndp proxy - hybrid
dhcpv6 mode - stateful only

client machine dhcp config as below-
"comment" Generate SLAAC address using the Hardware Address of the interface
"comment" slaac hwaddr
"comment" OR generate Stable Private IPv6 Addresses based from the DUID
slaac private