Actually, just found the solution. It was ESET Endpoint Security blocked the port. I have to add an exception to allow casting to work. I think it is resolved now.
Hi there, We recently bought 2 Vostro 5620. They run Windows 11, fully patched from MS. And fully updated with drivers and firmware via Dell SupportAssist.  Both machines are having troubles projecting/casting to Microsoft Wireless Display Adapters onto TVs. All the wireless display adapters have been updated to latest firmware. The two laptops will try to connect but eventually timed out.  Previously, I had problems with some Vostro 5510/5410 when casting kept dropping out (that is, connected but then dropped out). I found that by installing the Intel Iris display driver in place of the Dell OEM Intel driver, it resolved the problem. No luck this time. Just wondering if anyone has experience the same problem please? Thanks, Edmond
Vostro 5620 with Windows 11 unable to project to Wireless Display