I’m managing several Omnia routers (silver and black) all of them running on latest 5.x.
I have bought new USB sticks for all of them to preserve logs for post-incident analysis and thought fast (and expensive) USB 3.x sticks would be best. Also to preserver the rrd-graphs from collectd/luci-statistics.
As it turned out, after testing numerous products and brands, and also trying different pre-formatted file-systems, all of them lead to file-system errors after hours or days, many times also the router becomes totally unresponsive and needed a manual restart.
Only after some time and money I tried an old USB 2.0 stick. Guess what? No more file-system errors.
I also noticed, that changing USB sticks requires a cold-start, with a real disruption of the power-supply. Simply restarting the router with the reset-button or by command won’t recognize the change. It will just complain about the filesystem of the old one not being accessible.