This guide will provide you with the solution to fix the slow download speed issue you may be facing in fortnight.
It is mostly like just an inaccurate download speed indicator.
The download file size indicator keeps going up, but if this is not the case you will need to follow the steps below:
Exit the epic games launcher, then press windows key R and type %appdata%.
After that, navigate back to the AppData folder.
And then click on the Local folder.
Navigate to the Epic Games launcher folder.
And then the Saved folder.
Then configure > engine.
You will need to make sure it is not Read Only.
After that, copy and paste this text line.
[HTTP] HttpTimeout=10 HttpConnectionTimeout=10 HttpReceiveTimeout=10 HttpSendTimeout=10 [Portal.BuildPatch] ChunkDownloads=3 ChunkRetries=20 RetryTime=0.5
Save, close and then retry the download.
Hope it solves the slow speed issue.