Old Routers safe to sell?

[Allmightyballs]

Sorry if this is the wrong area to post. I wasn't sure where exactly this would be categorized 

Long story short, Ive had nothing but problems out of my ISP for 4+ years, during this time they've brought & left around 10-14 different routers and wifi boxes. I have multiples of each, some worked for a short time others stayed active for a year. It was like someone eventually got in the box and they just kept swapping them once I had noticeable problems.

 

I now have moved to a different ISP and want clear space, are these safe to reset & then sell? Ive seen while searching this question, some say No because pros who target people buy them and can Possibly recover stuff. Then Im seeing some people wanting specific models to fix home issues cheaper then their ISP(totally understand saving money). Im not looking to get rich but the amount of them I have might help on some bills and just the space savings alone.

Overall, Would they be safe to sell after a reset? If not what Info could they get or problems could happen if they did fall into the wrong hands?

Thanks 

 

P.S. Any info that might help me personally figure why they changed so many boxes would be appreciated. Last few times a tech guy came to "fix" things, they kept saying to each other, " I know I see it but I don't know what were going to do about it or why its there" Whatever it is they admitted was the reason and said I needed a new router, problem was still there within 2 minutes a new router hooked up. 

[Crunchy Dragon]

-Moved to General Discussion-

 

I also edited your title by adding a question mark to make it more clear that you're asking a question, not trying to offload hardware.

[aezakmi]

depending on the models you could reinstall the firmware or replace it for a different compatible version to delete any default settings

[Crunchy Dragon]

-Moved to Networking-

[Allmightyballs]

They are frontier versions if that matters. They all have a small reset hole/button so Ill just do that. That's what most people said would be ok but theres always one or 2 people saying don't unless you do a full DNS sweep and a lot more. I Always try to take caution when dealing with older electronics 

Thanks guys!

 

[Alex Atkin UK]

I'd love to know what they think a DNS sweep is and how it would be useful.  I can find very little mention of such a term on the Internet and nothing that seems remotely relevant.