1- One major reason SHAREit frequently disconnects while transferring files between devices is it tries to transfer data at highest speed which cause instability and disconnection. You may use a software that can limit the data transfer speed and improve stability. Besides SHAREit developers need to fix this problem by either reducing the transfer speed or write the software to make it stable at higher transfer speeds.
2- Placing devices at larger distance between which you are transferring files can cause signal drop or interruption caused by surrounding Wi-Fi networks. This would cause disconnection while SHAREit is sending or receiving files. Try placing devices as close as possible to make a stable connection between the two.
3- If SHAREit on PC is failing to connect with mobile or tablet, disable your antivirus firewall temporarily and try again. You may also try connecting with mobile SHAREit hotspot if PC SHAREit hotspot is not working.
• If file transfer fails due to the disconnection, you may resume it after re-connection. Note that resuming transfer process may corrupt the file. After transfer is complete check the file if it is working. If it does not you need to send it again. If you transfer APKs of applications and games or some other archived files and disconnection happens during the transfer process, you can resume it but there are greater chances that APK file during which failure occurred has corrupted. You can test it by opening APK file with WinRAR and run the “Test”. If no errors are found then APK is intact. Otherwise you need to transfer it again.
• There are other file sharing apps available for Android which can better transfer files over Wi-Fi. You should try those if SHAREit is not working for you. There are PC versions of some of those apps also available in case you need to transfer files between your PC and mobile or tablet.