We need your height/ weight and pics of what bikes you have to really see what is going on. Maybe the spokes are getting stressed sideways when you lean or climb on and off. Or the bike is too small, cheap ones often are.
I don't call them deFAILeurs for nothing. LOL ...Spokes breaking on tour bikes happen to over 60%, in my estimation. One average size guy broke 5 twice, on a LHT. SOME combinations of rim and hubs just do more poorly, IMO. Getting heavy spokes with the new wheel could have worked, but now is rather too late. 2 strikes and yer OUT. IMO.

The OP then answered his own question. Get a BETTER IGH bike.
I assume you don't want to spend thousands for a Rohloff bike so ....Look for a bike with a SA 5 or Nexus 7 or 8.
They are $800 to $1100. Or maybe you can find an old tour bike and replace the back wheel.
If you do build such a wheel, put 2.3/2.0 spokes at least on the drive side. If 35 mm tires, use a Velocity Dyad rim, that has NO goofy EYELETS.

I'm not big, but my custom tour bike rolls at 290/ 300 lbs. 8.000 miles like that, including some crashes too. My Rohloff has 16,500 miles with NO problems, including the shifter and cables. Only broken spoke was caused by my lock. The spokes are just straight 2.0 with locking nipples.
I have a SA dyno drum hub in front, with 24,000 trouble free miles. It has all 2.3/2.0 spokes. MY builds too, I haven't done many either.

There was a huge guy on YT who went on a tour in SE Asia. His LHT had the best derailleur hubs around. He broke 3 rims and 4 rear hubs, the pawls were breaking. THEN he got a Rohloff. LOL. Haven't heard from him the 6 years since.