Will Latitude E5570 drive a Dell U3417W 3440X1440 monitor at 60Hz

What kind of docking station are you using?  That resolution at 60 Hz would require a full DisplayPort 1.2 output directly from the GPU, so there are only a few ways to get that:

- Use a Dell docking station that attaches to the underside docking connector.  You will probably not be able to run a second display out of that docking station at the same time due to bandwidth limitations, though you can keep the internal panel active if desired.
- If your E5570 is a later example that includes USB-C, you could use a USB-C to DisplayPort adapter, but NOT a USB-C docking station, since USB-C docking stations sacrifice available display bandwidth to provide lanes for USB data traffic.
- If your E5570 has a USB-C port that includes Thunderbolt 3 functionality, you could use a TB16 dock.  You WOULD be able to add a second display to this dock since Thunderbolt 3 offers 2x DisplayPort 1.2 connections.

The final option would be something like a D6000 dock or other similar adapter that uses a DisplayLink chip in order to drive external displays, but those have some significant drawbacks compared to docks and adapters that tap directly into the GPU's native outputs like the solutions I mentioned above, so I would not recommend going this route.

One additional point of clarification.  With regard to the Dell docking stations that attach to the underside docking connector (the E-Port and E-Port Plus models), you'd have to make sure you bought one that includes 2x USB 3.0 ports on the back, because the versions that were updated to include USB 3.0 also received DisplayPort 1.2 support, which you will need for a display like that.  The original versions of the E-Port docks that only include USB 2.0 ports only support DisplayPort 1.1, which isn't enough bandwidth.

Thank you so much for the reply! I have a E-port PRO3X right now, it looks something similar to this - https://www.amazon.com/PR03X-Port-Replicator-PA-4E-Adapter/dp/B003L37KRE

It says 1xdisplay port and doesn't mention the version no. Do you think I am okay or should I order a E-port plus, something like this? - http://www.dell.com/en-us/shop/dell-e-port-plus-advanced-port-replicator-with-usb-30/apd/331-6304/pc-accessories

The main difference between E-Port and E-Port Plus is the extra set of display connectors and the legacy ports, so you wouldn't need the Plus version just to drive this display.  Just check the USB ports on the rear of the dock that are underneath the Ethernet connector.  If they're blue, then it's the newer USB 3.0 version, so you'll be good to go.  If they're black, it's the USB 2.0 version, in which case you'll need to buy the a newer version that includes USB 3.0.

Yes, the USB ports are black. I will need a new one. I found one on Amazon but it doesn't mention compatibility with E5570 - https://www.amazon.com/Dell-Port-PR03X-Adapter-Replicator/dp/B00L1FOR2K?th=1#HLCXComparisonWidget_feature_div

Although, if you look in comments, someone has used this dock with E5570 (searched for E5570 on the webpage)

One thing you MAY want to buy if you don't already have it with your current dock is the E-Dock spacer.  Newer Latitude models starting around the Exx40 series moved the docking connector right up against the rear edge of the underside.  Previous models had it closer to the center of the system.  That change in placement means that when an Exx40 or newer model is docked, there's more of a gap between the laptop and the rear portion of the dock, plus it's a bit harder to align the laptop with the docking connector.  So Dell released a plastic spacer in order to improve this somewhat, although it still does look a bit strange aesthetically.  This is a totally optional piece because the dock will work just fine without it, but if you want to buy it, here's a link: https://www.dell.com/en-us/shop/dell-latitude-e-docking-spacer/apd/452-bbtr/pc-accessories