U4021QW, 2018 MacBook Pro, hub buggy/unreliable

Hello,

I recently purchased the Dell UltraSharp 40 Curved WUHD Monitor (U4021QW) to use with my 2018 15" MacBook Pro (MBP). I'm experiencing buggy behavior that I haven't been able to resolve and I'd really appreciate any advice. Forgive the long-winded post; trying to be specific.

Setup: I'm currently running macOS Catalina 10.15.7 because IT restrictions prevent me from updating to Big Sur, so it's possible that these issues are specific to my setup and could be resolved with Big Sur. Dell Monitor is connected to MBP via Thunderbolt 4 cable provided with monitor. The following items are connected to the monitor: (1) ethernet; (2) Logitech BRIO Ultra HD webcam (USB); (3) standard Dell AC511 sound bar (USB; attached to monitor using 3M picture hangers since it doesn't attach properly); external hard drive for Time Machine backups (USB). 

Here are my issues and questions:

1. Unreliable ethernet: I experience an internet "outage" multiple times per day (including while writing this post).
2. 1. Disconnecting and re-connecting the monitor temporarily fixes the issue (until the next failure). The ethernet connection is still “active” according to Network settings in System Preferences when the ethernet fails (green dot, still has IP address, lights still blinking on ethernet port on back of monitor). What’s weird is that unplugging the ethernet port from the back of the monitor has no effect. MacOS still thinks the ethernet is connected (green dot, still has IP address). I assume this is because the monitor is still reporting an IP address? Not sure what's happening at a technical level.
   2. MacOS WiFi doesn't take over (can’t reach any websites), which I assume is because the OS thinks ethernet is still working.  This issue does not happen when ethernet is connected to the computer through adapter.
   3. I found another thread describing weird (but different) ethernet behavior with this monitor. The accepted solution is to install a Realtek ethernet driver. The user manual partially confirms, stating that we should install the Realtek driver from Dell’s website: “Install the Realtek USB GBE Ethernet Controller Driver available for your system. This is available for download at www.dell.com/support under the “Driver and download” section.”
   4. I do not see a Realtek driver for this monitor on Dell’s website, however, so I installed the driver on Realtek’s website at the previously listed link. Didn’t work. My ethernet still fails sporadically (no obvious cause I can see). Any ideas?
3. Unreliable USB speed (Time Machine Backups?): As mentioned above, I have an external hard drive connected to the Dell Monitor and my MBP is only connected to the monitor through the Thunderbolt 4 cable that came with the monitor.
4. 1. Every once in a while, I will do a new Time Machine backup from scratch, which I decided to last week. It was remarkably slow. After four days backing up ~850GB, it still wasn’t done. My computer actually wigged out on the fourth day and I lost both displays (Dell and MBP; I assume the Windows Server crashed), but the computer was still very busy and active. I SSHed into the machine and the backup was still going (slowly). This may all be unrelated, but…(see next point)
   2. I stopped the backup, restarted my computer, and started a new Time Machine Backup with the external HD attached to my MBP with an adapter. The backup finished in less than 1.5 days (started Saturday night and was finished Monday morning).
   3. Out of curiosity, I tested read/write speeds to this drive when connected directly to the MBP vs. the Dell monitor (using Blackmagic Disk Speed Test). Speeds were pretty similar between the two (~170MB/s reading and writing). I re-connected the external HD to the Dell monitor and my Time Machine backups seem to be quite slow again, but I don’t know a clear way to measure active disk activity for a specific process because iotop and iosnoop are basically disabled by macOS system integrity protection (SIP).
   4. Question: the monitor’s manual says that users can only use the USB ports on the monitor after connecting the provided USB Type-B cable provided with to monitor to the computer. The ports are clearly active without that, but is this required for maximum speed? I assumed I would only need to connect the USB-B cable if I was connecting to the monitor via HDMI or DisplayPort (i.e., not the Thunderbolt 4 cable), but the manual makes no specific distinction. Seems to suggest the user must always use the USB-B cable.

Anyway, really appreciate any advice. Please let me know if I can clarify anything.