zyxel fwa505 router trouble

Hi, we purchased the Zyxel fwa505 last year to solve our off grid internet problem. straight out of the box this dam thing has been noting but trouble, i can only get it to function and have internet connectivity rutting with zero security. the past 3 months the internet has been very limited and signal dropping off every few minutes. im about to bin th whole thing, my last resort is hoping theres a wizard out here willing to help me??.

Thanks

Callum