# Is it safe to purchase a second hand modem on eBay? **URL:** https://discuss.privacyguides.net/t/is-it-safe-to-purchase-a-second-hand-modem-on-ebay/38137 **Category:** Questions **Tags:** please-eli5 **Created:** 2026-05-26T01:46:03Z **Posts:** 9 ## Post 1 by @AnnieBee — 2026-05-26T01:46:03Z I have bought a new router to replace my ISPs router (which is no longer being updated so doubly problematic). Unfortunately despite my research I bought a flint 2 which I have discovered does not work with a FTTC connection and the type of authentication I need for my ISP. Full fibre is not yet available in my area. So I need a modem which does this (I can’t use my isp’s router as a bridge). I have found that these are available for a reasonable cost on eBay but I have no idea whether there are any privacy or security issues with doing this? Could someone download anything to a modem that could be used for nefarious purposes or for tracking or anything? Or any privacy/security issues I haven’t thought of? I’ve been nervous about asking this as I suspect this is a new really stupid question but I know very little and am gradually trying to build my knowledge and understanding which this forum has been invaluable for with its many very knowledgeable people. I have been caught out by my assumptions before doctoring not to make that mistake again! Thank you! --- ## Post 2 by @FranklyFlawless — 2026-05-26T05:35:45Z The most simplest solution is to ask your ISP what modems are compatible, and to either ask them to replace your modem for you, or as you are currently doing, bringing your own instead. --- ## Post 3 by @AnnieBee — 2026-05-26T16:10:11Z I did this first and they were zero help. They don’t provide modems and they were unable to tell me anything about compatible modems or settings. They no longer update the router they gave me at the start of the contract, and they won’t be providing a replacement. The “old” router can’t be used as a bridge. I don’t want to change contracts at the moment as I have a copper phone line currently included with my package, something which is becoming very hard, if not impossible to find, with other providers, and I want to hold onto it as long as possible as we have a lot of power cuts in my area which can take out all other communication. Having researched online this is a common issue with my ISP (not providing modem/setting info). So I’ve found out what I need myself, I just need to know whether there are any security or privacy concerns with buying a second hand modem from eBay before I do this. Thank you! :folded_hands: --- ## Post 4 by @TheDoc — 2026-05-26T16:41:04Z > [@AnnieBee](#): > > I want to hold onto it as long as possible as we have a lot of power cuts in my area which can take out all other communication. Off-topic but seeing as landlines are gradually disappearing, you’ll probably need to switch to an alternative at some point. Considering how bad this ISP sounds you might be better off figuring out off-grid communication alternatives sooner than later. I don’t know how much money you have to throw at the issue but large batteries, solar panels, satellite internet, and/or radios are often used for this sort of thing. > [@AnnieBee](#): > > I just need to know whether there are any security or privacy concerns with buying a second hand modem from eBay before I do this. My guess is there’d be a similar risk to buying a used PC which is usually pretty low. I’d research the seller’s reputation and consider re-flashing the router firmware if possible. --- ## Post 5 by @AnnieBee — 2026-05-26T17:55:25Z > [@TheDoc](#): > > Off-topic but seeing as landlines are gradually disappearing, you’ll probably need to switch to an alternative at some point. Considering how bad this ISP sounds you might be better off figuring out off-grid communication alternatives sooner than later. I don’t know how much money you have to throw at the issue but large batteries, solar panels, satellite internet, and/or radios are often used for this sort of thing. Yes I will be looking into more permanent solutions in due course. > [@TheDoc](#): > > My guess is there’d be a similar risk to buying a used PC which is usually pretty low. I’d research the seller’s reputation and consider re-flashing the router firmware if possible. I will be flashing the router, but I need a separate modem for now to make the router I have bought and want to use work, and its that my question is about. Is it “safe” essentially to buy and use a modem secondhand? I’m considering a Dreytek Vigor 130 or 166 or an old BT openreach modem if its relevant. Many thanks :folded_hands: --- ## Post 6 by @FranklyFlawless — 2026-05-27T02:03:33Z Well it depends on your threat model. Most modems cannot be easily reflashed with custom firmware, but if they can, then a malicious variant could be installed to actively and convertly exfiltrate network traffic in real-time. In addition, an advanced attacker could partially disassemble the modem and install hardware implants to perform similar attacks, bypassing custom firmware entirely. --- ## Post 7 by @AnnieBee — 2026-05-27T16:15:52Z OK so this sounds like you are saying this is something complex and unusual, that could possibly be used in a targeted attack? I am not going to be targeted by anyone directly (at the moment anyway! :grinning_face:), so I think the risk is extremely low? Have I understood this/what you are saying correctly? --- ## Post 8 by @Decoder — 2026-05-27T17:08:41Z Would not do it since it still carries a fingerprint and history is unknown. Never try to save a penny on such thing as privacy. --- ## Post 9 by @FranklyFlawless — 2026-05-27T21:51:30Z Yes, I would say that is a reasonable assessment, although even without this scenario, the firmware itself could be outdated, so your responsibly would be to update it once the item arrives.