Wifi signal strength issues

I've been having a problem with my wifi signal strength the last few days. Let me walk you through the trouble shooting I've done:

- I noticed the problem and walked closer to the wireless router and watched as the bars climbed back up. I walked away and watched them fall. Normally it was consistent throughout the house.

-I've placed my iphone 6 next to an old iphone 5s, ipad 4 and laptop. All on the same table. I then tested for signal strength and connection speeds. It was all very consistent across all the devices EXCEPT my iphone 6 which was slower and had a poorer connection.

-I got a bit more granular. Testing it's strength though walls and even its strength through my body if i blocked the wireless router with my person. In brief, it's having a very hard time picking up signals unless it's direct line of sight.

-Unfortunately it's not that simple. It seems to be intermittent. For instance, I'll be in a restaurant and check the available wifi connections and pickup dozens. A few moments later, I can see maybe 1 or 2 with weak signals.

-I've done a force restart with no avail. I'll try a full reset tomorrow but I'm not holding my breath. In the past with previous iphones when I had signal issues. Whether it was wifi or cellular the resets never worked.

In closing I'm curious as to what you guys advise. I'm leaning towards replacing the wifi antenna as it's a fairly cheap fix. Do you think that this might be the problem or are there other troubleshooting tips you might suggest?