iPhone 7+ The top volume button isn’t responding?

Hello! I have an iPhone 7 Plus (I’m not sure what ‘specs’ it is) OS version # 11.4 (15F79) and the increase volume button alone has decided to play dead and doesn’t do anything anymore whilst the decrease volume button responds and lowers the volume just fine.

For example clicking the top volume button appears to have no effect but clicking the lower volume button makes the ringer box with a bell in it appear on screen and the volume ticks down - increase doesn’t make it appear anymore.

I’ve tried wiggling it around, trying to make sure there’s in there around the edges but I can’t tell if anything’s blocking the button from connecting because the edges are so fine and hard to see into around it.

Pushing it down harder didn’t help.

The only thing that seems to work is manually bringing the ringer volume up from swiping the bottom of the screen up and changing it that way.