Having some issues with my wi-fi?

My wi-fi internet at home seems to be working fine on my laptop computer - moving at its regular speed and no concerns. However, on my iPhone, the Wi-Fi is extremely slow and at times can't even load sites or apps. This just came to be an issue today, so I don't know what could have changed to cause this. It should also be noted that my iPhone worked fine on the wi-fi network at work (no slowdowns) and works fine on cellular data. Any ideas as to why the wi-fi at home would suddenly stop working normally for my phone only?

First, I would try "forgetting" the network on your phone.
Go to the Wi-Fi settings, click on the "i" and tap on "Forget this network".

Re-connect, and hopefully it'll fix the issues.

If that doesn't work, you should reboot the router. Unplug it from the power cable, and wait about a minute. Plug the power back in, and connect your iPhone.

If that still doesn't work, you can reset the network configuration on the iPhone by going to Settings>General> Reset > Reset Network Settings. This will erase the list of all networks your iPhone has connected to.

After it resets, join your Wi-Fi network again.

As for why it happens, I don't know. There could be an issue with either the wireless router, the phone, or some bad configuration on either device.

This is frequently an issue with some devices, but not all, if your Wi-Fi is using the same or an adjacent channel to that being used by a neighbour. If your router is configured with a fixed channel, then the neighbour could have set up with a conflicting channel. Most routers use automatic channel selection and seek out the quietest channel. When you reset it, it probably allowed it to avoid the conflict that was causing your problem.

If it happens again, try fixing the router on a different channel. Try various channels. Remember this problem only affects certain devices and others seem immune for some reason.