With it play something like Youtube continuously without the connection dropping? Please test this.
If it doesn't drop Youtube then the problem is the local network, either at the server end (NAS/PC etc) or the X20. There haven't been any significant changes to the way X20 handles LAN connections between 1.2.28 and now so I would be looking at the NAS. Try disabling security features on the NAS temporarily to test and then, if that works, add X20 MAC address to the whitelist in NAS setup.