Ok so, after reaching the support, The sim card is only 4G, Bouygues Telecom don't allow multi sim with 5G on each sim card. Only 1 card at a time in 5G. So it explain why in my phone it worked...

EDIT: I just test a second time my sim card in my phone but this time only 4G and it also disable my 5g on the esim link to the same mobile plan. The router seems fine after all and the problem...

@David-TP Hello In 4G when it's working: In 5G when it's not working:

Bonjour, My brand new tp link 5g router won't connect to 5g. My sim card is from Bouygues Telecom in France (band n78) and is able to connect to 5g when in my google pixel 6 phone but is unable to...