What do You suggest? (Wireguard VPN) - Easy to setup
Deco X55 (EU) is ver 1.0  from Hungary. Latest firmware 1.6.1 Build 20241010 Rel.65389

My setup is 
Modem(bridge mode) - Main_deco (ruter mode) - smart switch  (Allied Telesyn AT-GS950 - Deco 2 (ethernet backhaul works fine) - Deco 3 (wifi connected in the midle of house).
I can tell you that this is working VERY WELL, without a even a one restart (14 days since electricity blackout)

Top pick is NordVPN, and Exlcussive offer is IPVanish in the APP. I want something, that can will work with future updates of firmware. 

I am satisfaided how DECO works. Do I need Security+, and if needed, is there will be some conflict?

Thanks in Advance, Chovus, from Serbia (Europe)