86.7 Mbps in your second pic is the raw communication speed between your wifi router and wifi adapter. Wifi protocols have a ton of error correction built into them which takes up most of that bandwidth. Typically, best case (device right next to the wifi router) actual throughput is about 1/2 the raw connection speed. In more realistic use (10-30 ft from the router) actual throughput of 1/3 to 1/4 the speed is normal. When the connection is poor (greater distances, more obstacles like walls, interference from neighboring wifi networks), it is not unusual for throughput to drop even lower.
So it's possible (likely even) that there is no problem with your ISP. To test the ISP's service, you really need to use a wired connection. If there's absolutely no way to run a bandwidth test over a LAN cable, use a laptop or phone (1) using 5 GHz, (2) 802.11ac, and (3) placed right next to your wifi router.
Can you tell us more about what sort of equipment you have (router, wifi adapter) and what your environment is like (apartment, house in dense suburb, house in rural location), and how many other devices you normally have connected to your wifi?