I split my home wifi and about a month later only 2.4ghz option shows

I have a couple of devices that need to be on 2.4ghz, and once my extender crapped out I thought to split to wifi instead of buying a new one. Everything was fine, I had everything on 5g except the ones that needed to be on 2.4g. Today all of a sudden everything was offline and I realized the only option showing is the 2.4g under available wifi connections. I went back on the mymodem page to make sure it hadn’t automerged it again, but no… Whole Home Wi-Fi is still off, i see the 3 networks (there’s 6g also), nothing has changed, but I still only get the 2.4g option… And I know it’s not merged bc the 2.4g devices are working fine. How do i get the 5g option back? It’s not a huge deal bc internet is still fast enough for what i need but not what i pay for (gigabit fibe 1.5).