I have a problem that I have been banging my head on for quite some time, so I figured it was worth asking for help. The lease on our Xfinity gateway/router combo unit ran up and against better judgment, my partner decided to replace it with a consumer grade gateway/router rather than buy separate devices. She purchased a Netgear CAX0 Nighthawk gateway and router combo unit currently running firmware version 2.1.5.2.
I was able to manually configure it without the use of the bloatware app that they wanted me to install on my mobile phone, and just about everything is in working order. The gateway connectivity to Xfinity is good and was provisioned an IPv4 address to the WAN. LAN and DHCP work fine, all devices get assigned LAN IPv4 addresses and network communication inside the LAN works well. The only difference from the previous router device is that DHCP is configured to the 192.168.1.0/24 block where on the prior device it was configured to the 10.0.0.0/24 block. Physical link via ethernet ports as well as WiFi works (albeit the range sucks but that is solvable).
The only problem that I cannot seem to solve is that ever since this unit was replaced, my mobile phone (Samsung S22), is unable to download media content for MMS messages while connected over WiFi (as well as inability to send MMS). I will get the initial SMS notification about an MMS message being available for download, however when connected to WiFi it will fail to download. If I disable the WiFi from my mobile phone then the message will download over Xfinity 5G just fine. Furthermore, connecting to a different WiFi network also allows me to download the message, it only ever occurs when my Samsung S22 device connects over WiFi to this new Netgear router and gateway. Interestingly my partners iPhone doesn't exhibit this behavior, although I admittedly cannot verify if the iPhone is event attempting any MMS messaging at all as I think it always sends media over RCS and converts incoming MMS into RCS prior to downloading the message content.
I have attempted a number of things to resolve the issue or at least get clues as to what might be happening. The following is what I tried:
Uninstalled/cleared data for Messaging apps on the Samsung device. Switched between Samsung Messages and Google Messages as the default messaging device on the Samsung. Enabled roaming downloads for messages Tinkered with all possible options in Messaging apps for MMS and RCS messages. Temporarily disabled all security/firewall features on the Netgear device. Removed the SIM card from the Samsung device, cleared the APN configuration for the mobile network, and then added the SIM card back in, and restored the APN configuration from it. Enabled advanced debugging in the Google Messaging app to obtain a message dump (SQLite database) so that I can identify download urls for MMS messages and attempt to analyze the route from my Netgear device to the MMS media download server (unable to connect over telnet at the specified port). Searching for others with the same problem, I can see that MMS downloads over Netgear routers is a fairly common problem, however it doesn't seem as if there is too much helpful here. I am unsure if MMS messages can ever be downloaded over a router unless it has its own SIM card for Xfinity, which I am certain my Netgear doesn't have, but I am uncertain if the leased Xfinity router may or may not have had one. Alternatively my mobile device was smart enough then to switch to the APN mobile connection when attempting to download MMS messages, however when the router changed, it somehow lost this ability (maybe from the private IPv4 address block change?)
I am really looking for clues as to if this is really a network issue at all or simply a software issue on my mobile device?
