What about the constant re-download of client_cel_1.dat?
Uninstalled, turned off everything from UAC, firewall, antivirus, flushed DNS, ran as admin, turned off and on router
and still....ERROR: File [ "D:\Games\DDO\client_cell_1.dat" ] failed MD5 check (SRC: "876a2fe2da46809e17f4802f6a152188" != LOCAL: "4f6a8afd8f643094d6bfe7f92f067032" re-downloading!
I have
Windows 10 Pro 64-bit
AMD Ryzen 5
RAM 16,0GB
Graphics 2047MB NVIDIA GeForce RTX 2060 (NVIDIA)