I noticed that my SMS 2FA for the banking is not working on Negros. I do not receive the 2FA SMS at all. Normally, they are delivered to my foreign phone number. On Leyte and on Cebu island I had not any issues on this case. How to fix this?
I had a similar issue, not in the Philippines, but might still provide some insite. My phone carrier changed spam filters which subsequently started blocking my banks short code that my bank uses to send me 2FA codes. https://en.wikipedia.org/wiki/Short_code says the Philippines uses seven digit short codes. I called my bank first. I provided them specific dates and times and they confirmed the message were sent. They assured me I need to call my carrier. Talking to my carrier, armed with my banks short code, I was able to get it unblocked. Your using a foreign phone in the Philippines combined with it working on other islands, that could be a daunting task, especially if the bank is also foreign to the Philippines. One could also suspect it possibly related to the application of the SIM registration requirement and how each local carrier is currently applying the requirement.
I found the issue. My phone uses a phone provider which allows WIFI-Calling. This works with SMS too. When I'm not on WIFI then the messages will not reaching me because I blocked roaming in my country due terribly high roaming cost. WIFI calling is still enabled because no cost for me. Therefore the bank SMS are only reaching me if I have working and stable WLAN available.
