Public IP Changes

Take away from that conversation, "PureVPN has a service with their VPN that assigns your connection with a dedicated IP address and port forwarding. It works with PPTP and L2TP / ipsec only but this makes it very easy to set up. PPTP is hardly encrypted and is not standard to use for many VPNs, but it is very very fast and is minimal on latency / bandwidth compromises. 

I use a second router with dd-wrt firmare and use PPTP to connect straight through its WAN connection settings. Super easy to setup, and the dedicated IP you assigned becomes the WAN IP of the second router which means port forwarding is used directly. No need to open any ports or DMZ with the t-mobile router at all. Routers will vary with PPTP WAN support, but this should be a pretty common protocol so others might work the same. 

This is actually easier than it might seem, and it works better than you might expect. The benefit is that you will also have a dedicated IP which is super handy to have. The downside is that there is a cost to these services, but PureVPN also supports OpenVPN so you can use to connect other devices as a standard VPN. Its a work around, but so far its the only way I have found to poke holes through that wall."

Maybe not what you really want to hear but it might just remove frustration from your life.

Are you running iOS 14 by chance? I recently encountered a problem with random session drops with my iOS devices when going out through the T-Mobile Nokia router. I found when I disabled the MAC randomization security feature for the wireless LAN that my problem went away. Apple's implementation of the MAC randomization was introduced by default in iOS 14. I had seen the disconnections over the past few months but it just became worse and worse. According to the information I found on the site, macaddress.io the implementation Apple uses randomizes the MAC address every 24 hours.

It runs kind of like a "public" VPN... your public v4 IP can potentially change anytime your modem restarts.  Many times it has actually shifted my "home market" as well, making apps think I was somewhere out in Kansas and such (I am in SC, typically homed to Charlotte).  Have to sometimes do a full power down and back up to get it to shift me back to Charlotte again.

No.  It's a Windows device that I notice the IP change from.  Anything I was connected to overnight gets disconnected and any firewalls I have my public IP added to have to be updated as well.

For me I describe the "random" session failures ad frustrating. The wireless connection would show strong and good to go but no internet would be the reported issue on my device. I can't explain why my wireless on my MACbook Pro is such a pain but a wired connection has resolved that just fine. The MAC randomization on iOS 14 devices, i.e. my iPhone 12 Pro and my iPad Pro going against the T-Mobile Nokia router was nothing short of pissing me off. I dont know if the public IP changes every 2 weeks but if you are having existing sessions that fall for no obvious reason and using iOS 14 it is good to be aware of this feature Apple enabled by default.

@djb14336 That’s funny.  I am in Kansas but the IPs I get are usually from Texas.  :)

With Windows 10 Microsoft also has an implementation of MAC randomization.

Do check out the macaddress.io FAQ section for MAC randomization. I have taken main focus on iOS 14 but I have multiple Linux clients using wireless and they are rock solid. My Windows 10 clients I use less but I have not seen obvious issues with those that I can directly relate to MAC randomization.

I SSH into Linux servers every day and I am sure it’s an IP change on the gateway’s part.

If I run across information that can help explain it I will try to pass it on to you. I am guessing a T-Mobile 3rd level engineer would have to provide clarification.