If you have a regular data plan that you use if your internet goes down, you’re server would technically have an internet connection, but your services (like email) still wouldn’t work would it?
Do you have some type of setup that keeps that working on data?
I don’t know how buying the ISPs data addon works, but I’ve been skeptical that the swap over would keep anything online either (but getting a generic data plan surely cant work at all right?).
So this sort of a setup is called Dual-WAN, and yes, it allows it all to work. Basically, my router has two connections to the internet- a cable modem on one port, which connects to Spectrum, and a cell modem on another port, which has my sim card on it. Both provide internet access simultaneously, and at that point, internet is internet- it doesn’t matter if it’s over data or through cable, you’re part of the net. My router is then configured to reach the internet via what it decides is the ‘best’ internet. In my case, because my cell connection is metered, I have it configured so that it prefers the spectrum connection, and only falls back to the cell connection if the spectrum connection is losing traffic, and only for as long as that connection is losing traffic.
Note that a dedicated cell modem is not necessarily required- some routers have sim card slots themselves, for exactly this reason, and tend to make this sort of configuration very simple to do. I’m personally using a small computer running OPNSense, which is again, probably overkill for the average homelabber, but you don’t need something that complicated.
As a result, my server always has access to the internet, and should you configure your firewalls appropriately (remember, I don’t personally run my own email- I have a custom dns name I point towards tutamail), the internet will then always have access to your server. There’s some details here and there about IP address caching, dns resolution, and the like which have various solutions from DDNS to an external proxy/loadbalancer/etc, but those are more implementation details.
For one, you have to now think about dynamic dns because you have your one static ip and then whatever ip your data backup will rollover onto. This isn’t ideal. Probably going to ruin any trust your domain will have.
Second, there is no way you’re getting a reverse PTR record setup to work in this config.
So, no, it’s not gonna work (clarification, technically may work, but you are gonna have issues and it’s probably not recommended).
It may work fine if you have random services, but tbh I don’t ever want to use or deal with a ddns service myself.
You do realize your DNS MX records can point to both IPs, and your primary connection just has a higher priority number, right? This is 2025, dns is outright expected to have multiple IPs behind it in varying levels of priority and availability. Just because the cell IP isn’t the active route for LAN-to-WAN traffic doesn’t mean it’s not connected or available for WAN-to-LAN traffic.
As for DDNS constantly rolling things, I’ve got, as I said, spectrum residential and my IP address has changed once in half a decade, and even then it was extenuating circumstances (I literally moved).
Finally, I literally mentioned that there were other ways around this, like an external proxy server on a static IP. Throw it on DO or something.
This is entirely viable for a email server. Would it be better to have two hardwire connections load balanced instead of a primary and failover that’s metered? Sure, if that’s an option in your area, then you just round-robin your DNS. But it still works just fine with a primary and failover.
Regardless, having two IPs for you email server is absolutely a complete non-issue. That was a solved problem ages ago.
Using the random ip you get from mobile data or using dynamic dns feels risky. Maybe that’s because I’m not smart, but the whole trust level is mail thing seems very heuristical and the risk of damaging my domains trust factor doesn’t seem worth it.
I’m not skeptical about having two ip addresses, but rather using ones that I don’t have control over (i don’t have the only right to use).
I might be wrong on the PTR record thing, seems it might be possible with DDNS providers but not 100% sure.
If you have a regular data plan that you use if your internet goes down, you’re server would technically have an internet connection, but your services (like email) still wouldn’t work would it?
Do you have some type of setup that keeps that working on data?
I don’t know how buying the ISPs data addon works, but I’ve been skeptical that the swap over would keep anything online either (but getting a generic data plan surely cant work at all right?).
So this sort of a setup is called Dual-WAN, and yes, it allows it all to work. Basically, my router has two connections to the internet- a cable modem on one port, which connects to Spectrum, and a cell modem on another port, which has my sim card on it. Both provide internet access simultaneously, and at that point, internet is internet- it doesn’t matter if it’s over data or through cable, you’re part of the net. My router is then configured to reach the internet via what it decides is the ‘best’ internet. In my case, because my cell connection is metered, I have it configured so that it prefers the spectrum connection, and only falls back to the cell connection if the spectrum connection is losing traffic, and only for as long as that connection is losing traffic.
Note that a dedicated cell modem is not necessarily required- some routers have sim card slots themselves, for exactly this reason, and tend to make this sort of configuration very simple to do. I’m personally using a small computer running OPNSense, which is again, probably overkill for the average homelabber, but you don’t need something that complicated.
As a result, my server always has access to the internet, and should you configure your firewalls appropriately (remember, I don’t personally run my own email- I have a custom dns name I point towards tutamail), the internet will then always have access to your server. There’s some details here and there about IP address caching, dns resolution, and the like which have various solutions from DDNS to an external proxy/loadbalancer/etc, but those are more implementation details.
Oh okay, so it doesn’t work then is what I’m gathering (for email).
That is, in fact, exactly the opposite of what I just said.
For mail this won’t work.
For one, you have to now think about dynamic dns because you have your one static ip and then whatever ip your data backup will rollover onto. This isn’t ideal. Probably going to ruin any trust your domain will have.
Second, there is no way you’re getting a reverse PTR record setup to work in this config.
So, no, it’s not gonna work (clarification, technically may work, but you are gonna have issues and it’s probably not recommended).
It may work fine if you have random services, but tbh I don’t ever want to use or deal with a ddns service myself.
You do realize your DNS MX records can point to both IPs, and your primary connection just has a higher priority number, right? This is 2025, dns is outright expected to have multiple IPs behind it in varying levels of priority and availability. Just because the cell IP isn’t the active route for LAN-to-WAN traffic doesn’t mean it’s not connected or available for WAN-to-LAN traffic.
As for DDNS constantly rolling things, I’ve got, as I said, spectrum residential and my IP address has changed once in half a decade, and even then it was extenuating circumstances (I literally moved).
Finally, I literally mentioned that there were other ways around this, like an external proxy server on a static IP. Throw it on DO or something.
This is entirely viable for a email server. Would it be better to have two hardwire connections load balanced instead of a primary and failover that’s metered? Sure, if that’s an option in your area, then you just round-robin your DNS. But it still works just fine with a primary and failover.
Regardless, having two IPs for you email server is absolutely a complete non-issue. That was a solved problem ages ago.
Hm, I’m gonna remain skeptical.
Using the random ip you get from mobile data or using dynamic dns feels risky. Maybe that’s because I’m not smart, but the whole trust level is mail thing seems very heuristical and the risk of damaging my domains trust factor doesn’t seem worth it.
I’m not skeptical about having two ip addresses, but rather using ones that I don’t have control over (i don’t have the only right to use).
I might be wrong on the PTR record thing, seems it might be possible with DDNS providers but not 100% sure.