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cfm56d7b

macrumors regular
Original poster
Aug 14, 2020
142
54
Hardware: 2020 Intel MacBook Pro 2.3 GHz / 16 GB / 1 TB
Monitors: 2 x Dell U2720QM 27" 4K monitors
Dock: OWC Thunderbolt TB4 dock (newest one); received it a few days ago

When both monitors are connected to MBPro directly via left and right TB4 ports:
- When waking up from sleep, both monitors are running in desired resolution: 3008x1692x60Hz

When both monitors are connected to MBPro via OWC Thunderbolt 4 dock:
- When waking from sleep, multiple problems occur
- Monitors resolution changes to 1920x1090 with monitor running at 60 Hz and the second at 30 Hz
- To change the monitor refresh rate from 30 Hz to 60 Hz, monitor TB cable has to be unplugged and plugged back in from the dock
- Resolution has to be changed again to 3008x1962
- Ethernet stops working
- Renewing the lease leads to self assigned IP
- Unplugging and plugging dock power cable solves the problem: Ethernet starts working, monitor resolution remains the same - 3008x1692

I will be calling OWC to report and discuss this problem.

There is a known issue with Realtek Ethernet driver and Big Sur.

Any insights or suggestions?
 
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