u/SLO_Fila

This problem really confounds me. So I have a Linode Shared Server with my website on it. My website has a SQL database which allows people to upload data into it using a form.

If I go to my website and try to upload data using the form, it works fine. But if I do it from outside of my wi-fi, it refuses to insert anything. I tried this using my phone and it works when connected to wi-fi but it doesn't when it is not.

Reading from the database works across the spectrum.

So I assume somehow linode or the sql database are filtering out anything that is not my IP but I never white listed my IP in the first place so I am very confused.

Note: When I used the old Ubuntu 12 server on Linode, this process worked fine. I migrated everything to a newer server with Ubuntu 24 and suddenly this has been happening.

This problem really confounds me. So I have a linode server with my website on it. My website has a SQL database which allows people to upload data into it using a form.

If I go to my website and try to upload data using the form, it works fine. But if I do it from outside of my wi-fi, it refuses to insert anything. I tried this using my phone and it works when connected to wi-fi but it doesn't when it is not.

Reading from the database works across the spectrum.

So I assume somehow linode or the sql database are filtering out anything that is not my IP but I never white listed my IP in the first place so I am very confused.

EDIT: Found the bloody error.

Oh man, I found the error and it was a doozy.

So it's a mix of things as I moved the server together with the database from the old ubuntu 12 to ubuntu 24, in the process updating to the latest versions of php, mysql etc. (move was from linode to linode).

The crazy "bug" was that I have a throwaway entry where I log the IPs of whoever inserts anything in the database (mostly for shits and giggles as I don't really use that for anything). Coming from the old ubuntu12 with the old code, it was IPv4 only so the varchar in the database was small to support an IP4.

Once I updated to the new versions plus I cleaned out the code a little bit, now the website logs IPv6 too. The problem was that the database was not set up to support the length of an IPv6 string.

So hence the reason why inserting worked when I was on my home WiFi (desktop, phone etc), because coming out of my router it was in IPv4 and the database could handle it. Using the mobile network on my phone, it uses IPv6 and the insert command would just die as the database couldn't log in the whole string.

But it took me about 6h to spot that bloody thing :/