Just thought I'd say I'm not sure who you's are hosted with but you really need to force them to upgrade the PHP used on your server as it's dangerously out of date. There's no severe vulverabilities currently but it's just a matter of time before there is. PHP 5.6 hasn't been supported for nearly 2 year now and I wouldn't be surprised if MyBB drop it soon since PHP 8.0 is out this year.

I could imagine the rest of the stuff on your host's server is similarly out of date - otherwise I'd seriously consider moving where it's hosted.

You're probably not aware just thought I'd say as it's my job pretty much.