Wireless Joint

Any recommendations for a setup I can build or a router I can purchase in Europe without paying crazy money for shipping from US? I currently have Teltonika router but it's disconnection constantly and UI is really not user friendly. Would love something with openwrt.

I need something that can also take adsl wan as well as dual sim for 4g and SMA connection for antenna

Also I am using Poynting uni directional antenna, but I see a lot of people here uses dual antenna setup, is that the best option?

Thanks in advance