Originally Posted by Grimmy3290
17 Winnebago vista lx 35b
OK, now that we know it's a motorhome, your best solution will be to install an Extend-A-Stay, or similar fitting to your LPG tank between the tank valve and your regulator. Although primarily created to connect an external tank to your MH's tank for additional LPG supply, the Extend-A-Stay device also provides a high pressure outlet to which you can connect a hose for a BBQ, camp stove or similar appliance that has its own regulator.
Here's a video that shows the installation process:
Amazon and other vendors sell the Extend-A-Stay and its clones for sale with and without the necessary hoses. Note that the hose you purchased probably isn't the hose you need.
There are pros and cons about tapping into your RV for LPG to run your BBQ including being limited as to location and having a hose that's a trip hazard. Another is to prematurely deplete your onboard LPG supply.
Personally, I have a small, 5lb LPG tank that I use for my camp stove and BBQ along with a propane distribution post (or tree) that allows multiple connections:
That way, I don't depend on the small 1lb propane bottles and can put my BBQ and stove anywhere I want it.