Apparently, IPv6 is still active. I requested Dual-Stack Lite to be converted to IPv4 Only, but it was in fact converted to Full Dual-Stack. IPv6 appears to be causing problems, while IPv4 works correctly. However, you made a typo on the PC traceroute.
You could set the DHCPv6 server operation mode to stateful, this occasionally resolves IPv6 connectivity problems. To do this, log in to the SmartWifi modem's web interface, go to the Advanced settings, DHCP page and select the Stateful option for the DHCPv6 server. Finally, disconnect and reconnect the phone to the Wi-Fi SSID.