iPhone won’t connect to 5ghz wifi’s

I’ve had my iPhone for a year and a half and this started happening 7 months in and I thought this would be fixed with a update but it never did fix it. I’ve restarted, reset network settings, reset my phone, literally everything. But it always acts up. It’ll sometimes connect but most of the time it just says “unable to join this network. None of my other electronics have this problem. My friend keeps saying it’s an iPhone thing and that they suck (she had a Samsung) I know it’s got something to do with my phone but I just want it fixed. It’ll connect to 2.4 ghz connections just fine but it’s extremely slow. I’ve tested it and I get like 1 - 24 mbs per second. I barely use my phone now other then pictures or calls and text, I’ve already had to replace my phone before due to a failed logic board so I don’t wanna have to go to apple. It’s also a newer model iPhone so I’d think itwouldn’t have these problems, it’s a iPhone xs max for reference. It also won’t connect to shaw mobile hotspots that my service provider lets me use for free so that’s a headache.