Xi6 does not recognize 4K splitter as 4K

I’m using an OREI UHDS-102 HDMI splitter to send the HDMI output to a separate TV.  When connecting this to an Xi-6 box, the output resolution of the Xi-6 box drops to 1080P (vs 4K). There is no way to adjust this apparently on the Xi-6 box.  My question, has anyone else run into this or used a different HDMI splitter that is recognized as 4K by the Xi-6?  Thanks to let me know