Best Hardware Solution to Increase Ring Pro’s RSSI

I recently installed the Ring Pro Doorbell. The Ring Pro’s RSSI shows a value that fluctuates between -61 and -75. We have several wifi enabled devices (Amazon Echos, Alexa, Kindle, as well as computers, phones, android cells, etc.) throughout our house. I’ve tried disconnecting some WiFi devices with little improvement in RSSI. My gateway, an AT&T U-verse Arris BGW210-700 (with voip telephone,iptv, dvr, DVR, ip internet) is in a straight line path, approximately 25’ from the front door. The wifi signal test inside the house at the front door shows a strong wifi signal at -65dbm on the 5 GHz band. However, the wifi signal test outside the house, next to the Ring Pro doorbell is weak, with a signal of -75dbm, on the 5Ghz band. Our house is a 1,250 sq. ft. modular house with vinyl siding. We live in a residential sub-division, which has approximately 6 networks. So what would you recommend to increase the signal strength to our Ring Pro; a wifi extender, or a powerline extender, or a router connected to the AT&T U-verse gateway? Your assistance is greatly appreciated! Regards, Rick