My Upload Speed Is Throttled at 6 Mbps (Motorola MG8702)

I can understand why this is frustrating. Based on what you've shared, I wouldn't expect a provisioning attempt to fail without further investigation. The fact that the modem is reaching expected download speeds but not upload speeds suggests there may be an issue with how the modem is provisioned on the account rather than a simple bandwidth limitation. If you'd like, our team can take a closer look at the account and modem provisioning to determine whether the correct configuration has been applied and whether any additional troubleshooting or escalation is needed. 
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@XfinityCarolyn @user_0axtgg 

The upstream power is too high / out of spec . That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/reconfigured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.

Also, check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, or animal chews.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

Good luck with it !

Quite welcome ! Good luck with it ! Please post back with how it goes.