I had the same problem and managed to fix it using the following method: (Windows 10)
My IP Configuration
PC 1 IP = 192.168.42.190
PC 2 IP = 192.168.1.6
PC 1 was connected to the router through a smartphone USB tethering, while PC 2 was connected directly to the router via wifi.
First, i pinged PC 2 from PC 1 using CMD ping, which resulted in a successful ping
Then, I opened Windows Explorer from PC 1 and entered the IP address of PC 2, followed by \ in the address bar:
\192.168.1.6
Pressing enter loaded the shared folders of PC 2 on PC 1. This enables transfers between both computers. However, PC 2 failed to ping PC 1, though it was still possible to share between computers as PC 1 could read and write to folders on PC 2
However, I noticed the transfer rates were a bit slower than they usually are. I use free file sync to sync files between two computers, and I was able to successfully sync my files using this method.