Have to throw in my coppers here:
Ran the MI424WR on the 120 build since it was installed (Jan/Dec(?)) and never had any real problems.
Closed port 4567 to shut off their updates, and had it shutoff in the advanced settings, but they forced one this last sunday (seems they have another backdoor) to 160.
Noticed Mon and Tue that the router would lockup and not respond to anything but pings (IE: no passthrough, no telnet, no web interface) and I would have to bump it to get it working again. Lockups would happen at random times, 2H to 6H.
Yes I'm running a custom setup, lots of changes (from the old 120) / but it ran fine on that one and config file loaded no problem / changes are QOS and Priority traffic on DMZ (few filters for games and DNS network objects).
In either case the port already mentioned should be closed and
IF you are ok on editing the config file then change the updates (IE: turn them off) as the web side does not do it:
(cwmp
(enabled(1))
(acs_url(https://cpe-ems1 ---trunicated----
(periodic_inform
(enabled(1))
(interval(86400))
change to:
(cwmp
(enabled(0))
(acs_url(https://cpe-ems1 ---trunicated----
(periodic_inform
(enabled(0))
(interval(86400))