Can't long-press ALT or CTRL, only once at a time [closed]

When I hold any letter key, naturally it keeps typing that key, or when I hold an arrow key in a game it will keep going in that direction.

However, in MapleStory, when I hold CTRL, it's supposed to continuously attack and when I hold ALT it's supposed to continuously jump, but instead, it does the action only once when I hold the key. This happens only with ALT and CTRL, I know because when I tried to move the jump action for example to another key and held it, it worked.

This only happens on my Dell 5577 gaming laptop with the built-in keyboard, works on my PC with the external keyboard. Haven't tried connecting an external keyboard to the laptop. I have Windows 10 on it, so maybe it's an issue with some settings?

The issue here is NOT about simultaneous keypress! It's about not being able to hold ALT or CTRL ingame and get continuous input. It does work with space and other keys, so I think it's something with the Windows 10 settings/BIOS settings but I couldn't find anyone with a similar problem as mine on Google. Again, it only happens with this laptop.

EDIT: Turning on Filter Keys and then turning on "Repeat Keys" to 0.3 seconds on both works as a semi-fix. After turning it on, when I hold ALT, it jumps every 0.3 seconds. But this isn't a proper fix because now there's a 0.3 second delay when holding ANY key on the keyboard. So now I know that IT IS a problem with Windows 10 and not with my laptop. Still not sure how to properly fix this, waiting for your help guys.