If your router is 802.11
ac and all of your devices are wi-fi
5 then you are already set because those are the same, provided everything is working fine. 802.11
n was rebranded to wifi
4 and honestly not much slower than ac as the major difference was a maximum of 40MHz wide instead of 80MHz on 5GHz--which only really works at short range. So
n to
ac would be an underwhelming upgrade and not worth much.
"Wave 2" ac went to 160MHz wide--which just about no clients supported until
ax. But it did turn out to be a considerable advance
at long range because the extra antennas (originally intended for downlink-only MU-MIMO which is useless for most people) worked great for
diversity which greatly improved range. And
ax has plenty of antennas too, so if you want to use 5GHz at long range then yes,
Wave 2 ac or
ax are better than
n or the original
ac.
On 2.4GHz though,
n and
ac are exactly the same (well, if you don't count the proprietary TurboQAM extension for Broadcom that's compatible with few clients--higher rate encoding schemes on 2.4GHz were not codified until
ax and it turns out these actually work pretty well on 2.4GHz because the signal doesn't fall off nearly as badly as with 5GHz. On
ac though, only Broadcom clients support it so it turned out to be useless like Super-G or Nitro 108G extensions for
g).
In general, clients for content consumption like your TVs aren't really helped by a faster connection, and content creation devices like a PC should really be wired. You upgrade wifi stuff if it's unreliable or otherwise not doing the job adequately, and that doesn't sound like the case here.