Channel 1 should be okay for you as there aren't many sharing that channel, but your router channel setting is set to Auto so that could change.
I use the full version of inSSIDer3 and not the Lite version - the one I use gives you the Link Score.
A problem can occur when other users have a signal strength within 20 of yours, but the other users are well away from you on that.
The channel setting should be in the router's wireless settings, but as these change from router to router, if you can't find those, then perhaps contacting your ISP or Googling for the steps for your make and model of router should help
50ft from the router is quite a distance, but the signal strength of -50dBm is a decent strength, so you should be able to get a comparable speed on your computer, although you can't really compare a mobile phone's wireless NIC to that fitted in a computer.
Is there a clear line of sight from the router to the laptop and have you tried the speed test with the laptop closer to the router ?
Is the drop in wireless speed a recent thing or has it always been like that ?
Sometimes changing the DNS servers can help if you still get similar speeds when nearer the router - I use Level3's DNS servers of 209.244.0.3 and 209.244.0.4
To do that, from the search, type ncpa.cpl and press enter when it comes up.
Right click on the wireless adapter and click on Properties.
Click on (TCP/IPv4) and then on Properties.
Click on the bottom button for Use the following DNS servers then type 209.244.0.3 in the top row of boxes, tab down and type 209.244.0.4 in the bottom row.
Check the box for Validate settings upon exit - OK - Close and that will invoke the troubleshooter which should report it can't find any problem.
You should end up having something like mine in the attached pic - click on the pic to enlarge.
Open a Command Prompt (Admin) or Powershell (Admin) and enter -
ipconfig /flushdns
ipconfig /registerdns
shutdown /r /t 00
then run another speed test after the reboot.
You can revert to your ISP's DNS default servers by going back into those Properties and clicking on the button for Obtain DNS servers automatically.
Age of the machine can also have an impact on speed.
I have two similar aged Toshiba laptops which have identical Realtek wireless NICs and an older Toshiba one which had a different Realtek NIC and I always had a much poorer wireless speed on that to the other two, so I took it into a repair shop and had them change the NIC which improved the speed.