Thanks for posting and welcome to the community.
The Solo 5 operates off of IR meaning that the Smart remote would need to be IR enabled.
Hector B - Community Support
Thanks for updating me on this. You won't be able to control the Solo 5 with this remote as you don't have ARC enabled on the Solo 5 due to the Solo 5 not having a HDMI port . Therefore this controller won't be compatible with the Solo 5.
Dec 31, 2019
Thank you for posting and welcome to the community. I would be happy to help with this.
It is odd that the Firestick remote is controlling the Solo 5. As the Firestick remotes are usually RF and the Solo 5 works with IR remotes, it should not be able to be controlled.
What functions on the Solo 5 are you able to control with the Firestick remote?