Peet Welthagen

It might be worth checking if your inverters suffer from the premature float bug, that might be your problem if batteries are not lasting. If that is your problem there are various workarounds before replacing them completely.

Great advice from @GreenFields
No need to change the panels. Even if 1 MPPT is working at say 18A instead of the 22A maximum it is a major saving retaining those 250W panels. There will always be someone interested in the 21st panel. Also although newer inverters have a lot more bells and whistles and extract more energy I would also not change the working Axperts just to get comms to work.
Although voltage settings don't work as well with lithium I am also using lithiums this way and works well for me. There might just be a bit of estimated SOC instead of getting the exact %.

Not to discount the advice,but this does sound kind of like "Buying a new car because the old one's tyres are old"
Better inverters can squeeze a bit more out or read more accurately,or have better apps,but if your sole reason is batteries that's not a good reason to upgrade
I'm also running dual Axperts on Voltage-mode with Hubble batteries in a bank,so not a dissimilar architecture to the suggestion above

Surely lots of people must be successfully running lithium ion batteries on Axperts using the voltage parameters, and the expected lifespan should still be much higher than for the previous lead acid batteries. Just not sure if that is the right reason to be replacing inverters if they are perfectly functional and serving your needs. The lead acid is just a technology with a lower expected lifespan, and that's not the fault of the inverter.

Good catch,just confirm the voltages on the panels and party hard!