Old 450 SMs starting to die in field

We deployed a lot of the original 450 SMs, I think it was 2015-2017, replacing 430 and FSK SMs. I realize these are old, but they do the job for subscribers on the lowest speed tiers.

Now we are starting to see a few die every month or so, the failure mode is they start rebooting every few minutes, and the log shows a power on reset. I’ve noticed that if the customer unplugs their router so the Ethernet link is down, the SM will last longer between reboots. Seems to me it’s a problem with the power supply circuitry inside the SM, and no Ethernet means it doesn’t have to supply as much power.

So are others seeing this as well? I’m trying to determine if these are just a few weak ones, or are they all going to fail this way eventually and it’s just a matter of time? If that’s the case, we probably need to bite the bullet and proactively replace them all during nice weather.

We have just over 500 original 450 SM’s still deployed. Some of these SM’s have been in the field for 10+ years. We’ve been slowly upgrading them to 450b’s as needed. We have not noticed any uptick in these older SM’s going bad. We’ve also kept our entire PMP450 network up to date on every new firmware release.