Melco and dac connections

[simoncn]

Thanks for all this information.

Some powerline adapters don't work reliably with UPnP. The best way to check this is to replace them temporarily with a long Ethernet cable. I have a 15m cable that I use for this type of testing.

The manual link you posted appears to relate to other Huawei router model numbers. On your router, I suggest you set Enable IGMP to No. This might disable IGMP snooping. IGMP proxy is something different and is not relevant to the issue you are seeing.