Time to get a replacement for the old SMCD3G-CCR?

I have a SMC SMCD3G-CCR with five static IP's, routing/firewalling is handled by an external device (the SMC doesn't have the memory/grunt to deal with my stack).

Recently, the SMC has started randomly 'hanging'.  My firewall stops being able to ping the public facing IP assigned to the modem, and traffic will not pass to or from the internal networks.  Every time, the problem has been 'resolved' by power cycling the modem.

In the time I've had it, it's been surprisingly reliable (after I turned off all the things on it and made it just pass packets), but as I was told by a sales rep that it has reached EOL, I'm thinking that I may want/should get it replaced with the current model before it totally dies.

Or am I better off sticking with the SMC as long as I can vs getting one of these newer devices made by Technicolor, the French company that started as a film processing company?

I don't need a field tech to 'install' the thing (and get charged for replugging a few cables), I just want it sent to me in the post.  If I can build a server from an empty chassis and bare motherboard, I can handle an equipment swap.

Besides, the last tech who came in to replace an earlier dead one took one look at my server and switch stack on the four post rack, just handed me the modem, and said they were not going to attempt to 'install/configure' anything as my setup was pretty complex looking.

What might be the process to get a newer model?  This kind of thing is part of the monthly cost of the rental as it was sold to me since comcast business won't let me run the necessary routing protocols on my own equipment (I just need packets moved, I don't care about/won't use anything built into the device)