@hTep
Hi,
The following instructions may be helpful in your case.
Deco SFP+ Ports User Reference Guide
The Deco BE85 does support using its SFP+ port as a WAN port, and it is generally possible to use an SFP+ ONU Stick (also known as a PON Stick) in conjunction with it to replace your ISP-provided ONT/ONU.
However, regarding the WAS-110 specifically, we are unable to guarantee compatibility, availability, or stability with this or any particular SFP+ ONU stick. The suitability of an SFP+ ONU stick largely depends on whether it has been verified and approved by your ISP. It is highly recommended to reach out to your ISP to confirm whether a specific stick (such as the WAS-110 with community firmware) is supported on their network.
Best Regards