Elastic IP from a local zone attached to instance being detected as IP from regional zone

From Elastic IP address basics and Allocate an Elastic IP address

When you allocate the Elastic IP addresses, you can associate the Elastic IP addresses with a network border group. This is the location from which we advertise the CIDR block. Setting the network border group limits the CIDR block to this group. If you do not specify the network border group, we set the border group containing all of the Availability Zones in the Region (for example, us-west-2).

As such, explicitly specify local zone network border group when you create Elastic IP. This will be ap-southeast-1-mnl-1 instead of ap-southeast-1.

Manila PH IP prefixes are

96.0.144.0/21
142.4.161.104/29
142.4.161.216/29

The above values are from ip-ranges.json. Note that geo-location tools may indicate them as Singapore IP even though these IPs are in PH

I am in Singapore, and here are my ping times to Singapore (8 ms) and PH LZ (44 ms) EC2 respectively

% ping 18.139.83.2
PING 18.139.83.2 (18.139.83.2): 56 data bytes
64 bytes from 18.139.83.2: icmp_seq=0 ttl=110 time=9.147 ms
64 bytes from 18.139.83.2: icmp_seq=1 ttl=110 time=8.832 ms

% ping 96.0.146.140
PING 96.0.146.140 (96.0.146.140): 56 data bytes
64 bytes from 96.0.146.140: icmp_seq=0 ttl=111 time=45.053 ms
64 bytes from 96.0.146.140: icmp_seq=1 ttl=111 time=44.441 ms

You may want to verify that your EC2 instance is in LZ subnet, and the local zone subnet's Enable auto-assign public IPv4 address setting is checked. As per Internet gateway connection to the internet, below is the architecture where top right EC2 in LZ is in public subnet (i.e. auto-assign public IPv4 is enabled) and has LZ network border group EIP associated with it.

To summarize, you may probably have to do the following

• Create EIP in ap-southeast-1-mnl-1 (verify that associated IP is in the list above).
• Check Enable auto-assign public IPv4 address for LZ subnet.**
• Stop your EC2
• Disassociate EIP from your EC2 (you can then release it)
• Associate the created PH LZ EIP with EC2
• Start the EC2

**If for some reason you do not wish to modify subnet setting, launch a new EC2 and Assign a public IPv4 address during instance launch. After which, associate your PH LZ EIP with the launched EC2