Please check the following points.

(1) DNS setting might not be "Automatic acquision". Please refer to the following web site and acquire the DNS server address automatically.
(2) Please confirm whether connection from your IP address is allowed. Your IP address can be viewed at http://www.iimc.kyoto-u.ac.jp/ip
(3) In case of IKEv2 on Windows machine, please go to [Properties] of VPN --> [Network] tab --> [Properties] button of [Internet Protocol version4(TCP/IPv4)] --> [Advanced...] button then confirm if "Use default gateway on remote network" and "Automatic metric" are cheked.