Unable to connect to Realms

Issue: I am unable to connect to Realms using a BT Smart Hub Router (ADSL) (United Kingdom).

1. I followed all known advice including amending router settings and security software settings. This did not resolve the issue.

2. In addition i deleted the realm and cleared the cache, this did not resolve the issue.

3. As a further test i connected via a 4G Hotspot, this allowed me to connect to realms without issue.

Screen Prints: There are none because the screen encountered is simply the "Loading Resource Packs" screen.

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System Configuration:
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Machine: Dell Inspiron 15 5000
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Op System: Windows 10 - Version 1909 - OS build 18363.778
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Network Speed:

• 46mbps - Download
• 9mbps - Upload
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  Network Performance: All other internet based software works on the device. Only Minecraft is failing.
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  Router Security:
• Device was moved to the DMZ
• Router firewall was disabled
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  Software Security: Norton Security Ultra - 1. Smart Firewall was disabled
• 2. Auto-Protect was disabled
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  Observations ....when i connected via a different network (4G Wifi Hotspot) there is no issue, even if i put my Norton Firewall on. Also, the game runs smoothly offline.
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  Please can you offer further advice or investigate for a bug? My conclusion is there is a bug somewhere in the build.
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