Connections will work fine within any PHP version from 5.2.4 to current, so a PHP update should not have any effect. I actually dev Connections on PHP 5.4.15.
The thing with setting the PHP memory is, it can be set to anything and PHP will happily report the memory limit being set and not report that the host could have a hard limit set. Maybe when they performed the update, they accidently changed that hard limit. Unfortunately they only way to know is to ask their support.
Could you also check the PHP error log? Maybe something will be in there that will shed light on the issue.