Deutsche Telekom has been one of the most stable of the major European telcos in recent years. Its debt mountain, while large, has been more manageable than that of peers such as TIM and Telefónica and by contrast with Vodafone’s albatross venture in India, it has been buoyed by the recent success of its US holding, T-Mobile USA. Its first quarter results, announced last week, were happy reading for shareholders, with a rise in profit and in full-year guidance, boosted by TMO and the sale of a share in DT’s towers operation. However, underneath solid figures there are warning signs of challenges ahead. Like all the European leaders, DT faces rising capex bills to support 5G and fiber expansion, and…